Erratic engineeress

A personal blog fuelled by caffeine and curiosity.

How to cook with food scraps to reduce food waste

It’s not waste until we waste it.

Since I got back from my studies abroad and moved in with my boyfriend, I’ve been trying to establish a greener household with less waste. Turns out, it’s actually quite easy to adapt most of our daily habits in a less wasteful way without going to any extremes, which includes food waste.

Personally, I rather dislike the term zero waste, because it is impossible to live without any waste at all, but I do believe that we should all try and reduce our environmental impact, particularly where we easily can (same goes for less waste travelling). As you probably know, we waste tons of food allover the world every year, so I’ve been looking for ways to use up all of my food scraps and waste as little as possible.

I’ve found quite a few ideas and today I want to share the good ones with you. There are many different types of food scraps and leftovers, so some of these ideas might be a bit out of the ordinary, but keep an open mind and let’s get started! 🙂

How to use up vegetable leaves

You know how carrots and beetroots etc. sometimes come with leaves? Most people tend to toss them out or use them in a soup at best, but there’s a much more delicious option: make pesto.

The original pesto is a spread made with fresh basil leaves and pine nuts, but you can make something similar with pretty much any kind of edible vegetable leaves and nuts. I’ve made improvised pestos with kohlrabi, beetroot, radish and carrot leaves so far, most often paired with cashews.

The procedure is super simple: wash your chosen leaves, toss them into a good blender, add a bit of salt, a handful of nuts and plenty of olive oil. You can also play around with adding garlic, black pepper or lemon juice to correct the raw vegetable taste if it’s not to your liking. Blend it until smooth or just a bit chunky according to what you prefer, store it in a container and enjoy. The end result should have the consistency of a spread and the pesto will keep in the fridge for about a week, just make sure it’s always slightly topped with olive oil to prevent it from drying out or getting mouldy. You can use it on bread, pasta or anywhere else and it usually goes great with parmesan or mozzarella cheese.

I find nuts with neutral flavour such as cashews or pine nuts work best with any leaves, although peanuts also go great with stronger tasting vegetables like kohlrabi. I suppose almonds, walnuts and hazelnuts could also work, but I associate them with sweet flavours, so I haven’t tried. If you want a proper recipe, here is a pesto recipe for any kind of green garden scraps.

P. S.: If you can’t eat nuts, you could replace them with sunflower, linen or sesame seeds and see where the taste takes you.

P.P.S: If your vegetables come with thicker stalks or green, thick outer leaves like cauliflower, use those in mixed one-pot soup with some beans, lentils, chickpeas etc.

This soup was almost entirely made of extra vegetable stalks and scrap soup stock (described below) and it was awesome.

How to use up leftover egg whites and aquafoba


Many baking recipes call for egg yolks, so you’re left with lots of boring egg whites. Egg white omelette is fine on a diet, but snowballs and meringues are better!

Fluffy egg white snowballs are a nostalgic dessert in Slovenia and Germany and my grandma makes the best ones. You can either make them with custard, for which you’ll need egg yolks too, or with a simple vanilla or chocolate pudding sauce.

As for meringues, they probably don’t need any introduction, since they’re the fluffies, puffiest type of dessert out there.

At this point you’re probably wondering what the heck is aquafoba. I did too and it is bean water or brine, the salty water in which beans, chickpeas, lentils and other legumes were cooked in. Apparently that somewhat icky, slimy brine is a great egg substitute, as the vegans have figured out that it acts the same as eggs in almost all baking recipes, so if you don’t eat eggs, this one is for you (recipes here).

How to use up leftover brine

Next up we have non-bean brine, the pesky liquid we’re all always left with by the jarful. If you love pickles like I do, or even if you just like eating cheese that comes in a liquid, you’re probably already out of ideas on what to do with it, so here’s a new perspective:

  • Use it as a salad dressing: if your brine is sour, you can use some of it it as a salad dressing for your next vegetable/lettuce salad. Just add a bit of oil and salt and you’re set! Same goes for oil-based brines, like the oil from a jar of sun-dried tomatoes, and you can also use those for a bit of extra flavour the next time you’re pan frying something.
  • Make rice salad: rice, quinoa or couscous cold salads are awesome as healthy take-to-work lunches and if you’ve ever made one, you probably know that the grains like to soak up a lot of liquid over time. Seasoning them with brine is the perfect way to end up with a not too sour, flavourful salad and you’ll use up a lot of brine in the process. You can make them with anything: vegetables, cheese, fish, ham… the possibilities are endless, so here are couple of rice salad recipes for inspiration.
  • Use it as a meat/vegetable marinade: turns out you can use pretty much any type of brine, even mozzarella cheese liquid, as a meat/vegetable/meat alternative marinade. Put your chosen food item into a container, fully submerge it in brine, add a bit of seasoning and leave it to marinate in the fridge overnight. I find it works best with bland meats like chicken and turkey, but if you’re marinating meat make sure the brine is not too salty or your meat may get tough after you cook it. Don’t be surprised if a lot of liquid comes out of whatever you’re marinating if you roast it, because sour brines tend to absorb more – just let the water boil away in the pan and continue on as normal until the food is nice and crispy. P.S: Remember to toss out the brine if you used it to marinate raw meat or stuff like tempeh and tofu.
  • Use it as a glaze: if you’re aiming for a sweet and sour dish, you can use leftover sour brine as a glaze at the end and it works great.
  • Reuse for a quick pickle: you can also reuse the brine for another round of pickling by tossing in some fresh vegetables (or even cheese) with extra seasoning. Keep it in the fridge, wait a few days before eating and remember that it doesn’t have the same expiration date as a properly prepared pickle.

This article has some other crazy ways of using brine and other leftover liquids, such as whey, just remember that there’s a limit to how many times brine should be recycled and that there comes a time to toss it out.

How to use up food scraps

When you’re preparing a meal you will naturally end up with food scraps, but they don’t need to be food waste right away. Make them work for you before tossing them out instead, by making scrap soup stock. I know it sounds weird, but hear me out: everything you cut away away from your vegetables is essentially food.

Carrot ends, dried onion layers, apple cores, cabbage cores and dry outer leaves are all food, we humans are just too spoiled to eat them if we don’t absolutely need to. If you boil them they make excellent vegetable broth that you can use as soup stock for soups, sauces, risotto etc. + you’ll never need to buy soup stock/broth in the shop again. This is not a new hipster thing, our grandmothers did it and people all through history did it, particularly in times of crisis, and you can find recipes for it allover the Internet (here’s one).

The idea is simple: collect all food scraps until you have enough to make soup. You can keep them in a zip lock bag in your freezer to prevent them from spoiling, or you can keep them in a jar on the kitchen counter like I do. I find that most dry scraps will keep for up to a week if kept in a jar covered with a cloth, while wet scraps like tomato cuttings, meat/fish bits etc. should be kept in separate containers in the fridge up to a few days (particularly the meat/fish bits!). If you cook as much as we do, you’ll be left with tons of soup stock in a matter of weeks and it really adds a ton of flavour to anything you cook.

Make sure that whatever scraps you’re collecting have been thoroughly washed, which is particularly important in root vegetables (you don’t want dirt in your soup!). There are different approaches to making scrap soups, but personally I always roast the scraps on a bit of butter first, add salt (use more than normal to make a stronger soup stock), bay leaves and some juniper berries. I don’t use other seasoning, because I want to keep a pure soup base for whatever dish I’ll be making, natural flavour only.

Add water, boil it for about an hour or until you’re left with a small amount of liquid, drain it through a sieve and into a container. I like to freeze my soup stocks and pop them out directly into whatever I’m cooking, so choose containers with a wide opening. Some people freeze them in ice cube trays too.

What goes into a scrap soup? Whatever you want, but think soup – any vegetable tops, outer leaves, pumpkin and pepper innards, dry parsley stalks, meat/fish cuts and even some fruit scraps (apples, strawberry tops etc.) if you don’t mind a sweeter flavour. The trick is in boiling it for long enough to squeeze out the flavour and in adding extra salt to enhance it, but they usually turn out quite strong either way. I advise against using potato scraps unless you’ll be making the scrap soup the same day, because potato peels like to turn blueish after a while and I’m pretty sure that’s not good. Also, make sure you’re not adding anything rotten or mouldy, that goes straight into the trash. Remember to label the soup bases somehow so you’ll know what flavour to expect when cooking.

How to use up the rest of food scraps

Even if you’re making scrap soups there are still some food scraps you can’t just eat or use in a soup, so here are some more ideas:

  • Peel chips: If you like vegetable chips/crisps like these, you should start making them from scrap peels. Potato, sweet potato, carrot, beetroot etc. peels are all edible, full of healthy stuff and quite tasty, so if you wash your vegetable before peeling it you can make peel chips by tossing the peels in the oven at 200°C for 15 min, with a bit of oil, salt and seasoning (paprika and chilli work great).
  • Apple cider vinegar: you can also make apple cider vinegar from apple peels and cores if you cover them with sugar.
  • Infusions: you can use lemon (or any citrus) peels to infuse honey, water or olive oil with a bit of extra flavour or to make candied peels. Just make sure your citrus peels are not full of pesticides. P.S.: I recommend adding some rosemary, garlic and chilli to the lemon infused olive oil – you just toss everything in, leave it for a few weeks, strain and you’re done. Or you can boil them with some ginger to make tea. You can also dry and save ground lemon peels to use in baked goods and desserts.
  • Bread dumplings from stale bread: if you have leftover hard and stale bread, you can give it new life as breadcrumbs, croutons or as bread dumplings. They’re soft, delicious and perfect as a side dish (more about them in my blog post here and recipe here).

How to use inedible food scraps

And then there are the things you just can’t eat, no matter how much you may want to. 🙂 However, some of them can still be useful:

  • Banana peels: they can be cut into little pieces and used as fertilisers for your plants. Same goes for leftover loose leaf tea and coffee grounds, just make sure you dry them first to avoid mould. You can also use tea and coffee grounds in homemade cosmetic peelings or soap.
  • Pits and seeds: Avocado pits can be used to grow new avocado houseplants quite successfully, as well as pepper and chilli seeds. Other food waste can also be planted, but growing an indoor apple tree from apple core seeds is quite a bit more difficult for example.
  • Onions peels: the dried up outer onion layers can be used to colour Easter eggs if you boil your eggs with them. In my family we like to tightly wrap up the eggs in a piece of nylon tights with different plants, so they leave pretty leaf patterns on the eggs (see the details here).
  • Eggs shells: you can use washed egg shells as planters in which to sprout your plants. You can even plant them directly into the soil with the egg shells, which are full of minerals, just crack them a bit at the bottom to give the roots the space to expand through.

That’s it! The rest of the food scraps will unfortunately need to go straight to the garbage, unless you have some other ideas on how to use them (let me know in the comments). 🙂 I hope you learned something new and are now considering joining me on my food waste reducing wagon – everyone is welcome!

If not (yet), then at least remember the most important rule of avoiding food waste: you can always freeze bits of food for later use and reuse leftovers in a new dish instead of tossing them out. Here are a couple more practical tips on reducing food waste and repurposing leftovers and a couple of historical dishes from troubled times, but if you want to see the real pros at waste cooking, then check this out.


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15 responses to “How to cook with food scraps to reduce food waste”

  1. Hi. I tagged you in my post “The Perfect Book Tag.” Please feel free to participate, I’d sure enjoy it. If you’re too busy or don’t want to, I understand, but if you can do it or a portion of it, that would be cool. Thanks, Herb

    1. Hi, I’ll come check it out! 😊

    1. Thanks, maybe your cooking beloved would find it interesting.

      1. We grow about a quarter of our own groceries! I will let her know!

      2. That’s awesome! I want to have a house with vegetable garden someday, right now we just grow fresh herbs.

      3. I have oregano, sage, and thyme

      4. Pretty nice! We’re currently sprouting carrots, coriander, dill, basil, wild garlic, onions, radishes, and water cress. We also have oregano, thyme, little chillies, lavender and parsley, but some of them have plant lice and I don’t know if they’ll survive.

      5. Wow! Pretty neat! Have you thought about making a garlic or pepper spray to repel and kill them?

      6. Didn’t try that, we sprayed them with a water mix of an eco dishwashing detergent in tiny quantities, so I hope it won’t be a problem if we eat them in a few months. Seems to have worked so far

      7. Very neat. Sometimes the smell throws them off.

      8. I’ll try that next time, seems safer that eating detergent.

      9. Ha ha! I suppose. Can you light fireworks in your country?

      10. Not unless it’s Christmas time, it’s only legal for about 10 days in December.

      11. Oh, bummer. We can use some types like fountains and sparklers year round.

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