Cooking with food scraps: use up every bit

When you throw away vegetable peelings or a crust of old bread, you're binning something you already paid for. Our guide to reducing food waste covers the big picture — this guide is the practical companion: what to do with the scraps you would otherwise bin.

Uses for common kitchen scraps

Vegetable peelings and offcuts

• Carrot peelings, ends and tops: peelings and ends go into your stock bag. Carrot tops are edible and slightly bitter — blend them into a pesto with nuts, garlic, olive oil and lemon, or use sparingly in salads.
• Onion skins and papery layers: golden and brown onion skins add a rich amber colour and savoury depth to stock. Wash them first. The tough outer layers that you'd normally peel off entirely are ideal.
• Celery tops and leaves: the leafy tops taste like celery and work well in stock, soups, salads or as a garnish.
• Leek greens: the dark green tops are usually discarded but are perfectly edible. Wash carefully (grit hides in the layers) and use in stock, or slice fine and cook down slowly in soups and stews.
• Broccoli and cauliflower stalks: the stalks are just as edible as the florets. Peel the outer skin if it's tough, then slice or dice — they work well stir-fried, roasted or grated into slaws. Leaves are edible too.
• Mushroom stalks: slightly tougher than the caps but full of flavour. Add to stock, or chop fine and cook into sauces and fillings where texture matters less.
• Corn cobs: after cutting off the kernels, simmer the cobs in water for 30–40 minutes for a sweet, light stock that's excellent in corn chowder.
• Herb stalks: parsley, coriander and basil stalks have plenty of flavour — add to stock, blend into sauces, or chop fine and use wherever you'd use the leaves. Rosemary, thyme and bay stalks go into stocks and braises.

Stale bread

• Breadcrumbs: blitz stale bread in a food processor, or rub it on a grater. Dry fresh breadcrumbs in a low oven (about 120°C/250°F) until crisp. Store in an airtight container for weeks. Use as a crisp topping for baked dishes, pasta, salads or fried as pangrattato.
• Croutons: tear or cut into chunks, toss with oil and salt, bake at 180°C/350°F until golden. Add herbs or garlic.
• Panzanella: the classic Italian salad made almost entirely from stale bread, tomatoes, olive oil and vinegar.
• Ribollita, bread soup, or French onion soup: dishes built around stale bread that absorbs liquid beautifully.

Citrus peel

• Zest before you juice — it's much easier and you won't miss the opportunity. Freeze zest in a small container.
• Simmer citrus peel in water with sugar to make candied peel or a simple syrup for cocktails and baking.
• Use citrus peel as a natural cleaner: steep in white vinegar for a couple of weeks, strain, and dilute with water for an all-purpose cleaner.

Overripe fruit

• Bananas: freeze them whole; blend frozen for banana ice cream, or defrost and mash into banana bread or pancake batter.
• Berries, stone fruit, citrus: blend into smoothies, cook down into compotes or jams, or use in baking where a slightly softer texture is fine.

Pickle brine

• The brine from a finished jar of pickles is flavoured vinegar. Use it as a salad dressing base, in marinades, to quick-pickle other vegetables, in potato salad, or as the base for a Bloody Mary.

Bones and carcasses

• Chicken carcasses, pork bones and beef bones all make excellent stock. Roast first for a deeper flavour (or use straight from a roast). Cover with cold water, bring to a simmer, skim off any foam, and cook for 2–4 hours (chicken) or 4–8 hours (beef and pork). Strain and use or freeze.

The freezer stock bag

The single most useful habit in this guide: keep a bag or container in the freezer and add clean vegetable offcuts as you cook. Over several weeks it fills up with onion skins, carrot peelings, celery tops, leek greens, parsley stalks and whatever else you trim. When it's full, you make stock.

The bag keeps indefinitely in the freezer, so there's no pressure to use scraps immediately. This is what makes it practical — it works with your normal cooking rhythm, not against it.

Good additions: onion and leek offcuts, carrot ends and peelings, celery, mushroom stalks, herb stalks, corn cobs, tomato skins.

Use sparingly or avoid: very strong brassica stems (can make stock bitter in large quantities), artichoke leaves, very starchy vegetables like potato peelings (cloud the stock).

How to make vegetable stock from scraps

1. Prepare your scraps. Tip the frozen bag of vegetable offcuts into a large pot. No need to defrost — they go in frozen.
2. Cover with cold water. Add enough water to cover the scraps by a couple of centimetres. Starting with cold water extracts flavour more evenly.
3. Bring to a gentle simmer. Over medium heat, bring the pot to a simmer — not a rolling boil. Boiling hard makes stock cloudy and can make it bitter.
4. Add flavourings. Add a bay leaf, a few black peppercorns, and a small pinch of salt if you have them. A splash of white wine adds depth.
5. Simmer for 45–60 minutes. Partially cover. Taste after 45 minutes — it should be savoury and flavourful. Continue if it needs more depth.
6. Strain and cool. Pour through a colander or fine sieve into a bowl. Discard the solids. Let cool before storing.
7. Store. Refrigerate for up to 5 days, or freeze in portions (ice cube trays work well for small amounts). Label and date.

What NOT to use

• Mouldy food: do not cut the mould off and eat the rest for soft or high-moisture foods. Mould toxins (mycotoxins) can spread through the food invisibly. Hard cheeses and firm vegetables are a different matter — a small spot can be cut out with a generous margin — but if you're not sure, bin it or compost it.
• Rhubarb leaves: the stalks are edible; the leaves are not. They contain oxalic acid at levels that can cause illness. Always discard them.
• Green or sprouted potatoes: the green colour and sprouts indicate solanine, a natural toxin. Cut away any green areas and sprouts generously before cooking, and discard if heavily affected.
• Off-smelling or slimy food: trust your senses. If it smells wrong, composting is the right call.

Compost what's truly left

Even with good scrap cooking habits, some waste remains: mouldy food, used stock scraps, eggshells, tea bags, coffee grounds and genuine offcuts that can't be used. These are exactly what compost is for — they become free soil amendment rather than landfill methane. See our composting guide for how to get started, even without a garden.

Your checklist

• Start a freezer stock bag today — a zip-lock bag or any freezer container works.
• Zest citrus before juicing and freeze the zest.
• When bread goes stale, blitz into breadcrumbs or make croutons rather than throwing it away.
• Cook broccoli and cauliflower stalks alongside the florets — peel, slice and roast or stir-fry.
• Use herb stalks in stocks and sauces instead of discarding them.
• Keep a compost bin for the scraps that genuinely can't be cooked with.