White onion

Use a sharp knife, which crushes fewer cells, and chill the onion for about 15 minutes first. Cut it in half from root to tip, then peel and slice; leaving the root end until last can also help.

For caramelised onions, slice them thinly and cook in a little oil or butter over low heat for 30–45 minutes, stirring often. They should turn deeply golden, not black; add a splash of water if the pan starts to catch.

Keep a cut onion in a sealed container in the fridge and use it within a few days. Store whole onions somewhere cool, dry and well ventilated, away from potatoes.

Their crisp texture and sharp flavour work well raw in salsa, pico de gallo and salads, or cooked in soups, stews and fajitas. Dice them finely for salsa so they blend with the tomatoes rather than dominating each bite.

Yes: use the same amount. White onion tends to taste sharper and crisper, while yellow onion becomes sweeter and more rounded when cooked.

White onions have a sharper, more savoury bite; sweet onions are milder and sweeter, especially raw. You can swap them in most recipes, but a sweet onion may make a dish taste noticeably less pungent.

Slice or dice it, then soak it in cold water for 10–15 minutes and drain well. This softens the sharp bite while keeping the onion crisp for salads, sandwiches and salsa.