Spring onion

A spring onion is a young onion picked before its bulb swells, with a slim white base and long, hollow green tops. Americans call it a scallion or a green onion, and the three names mean the same thing in a recipe. Some UK shops label them salad onions.

The whole thing is edible apart from the root and any limp outer layer. The white and pale green part tastes like a gentle onion and can be cooked; the dark green tops are milder and fresher, and are usually sliced and scattered over at the end.

That split is why stir-fry and noodle recipes often say to slice the whites and greens separately: the whites go in with the garlic and ginger, the greens go on top. Raw, they suit salads, salsas, mashed potato (as in Irish champ) and omelettes.

Trim the root, peel off any slimy outer skin, and slice on a slant for longer pieces. Store them in the fridge and use within a few days.

In parts of the US, "spring onion" can mean a larger, bulbed young onion, but in British and most American recipes it is the slim one.