Basil

Basil is not just a smell you add at the end. Drop it into a hot pan too early and you'll watch it happen: the leaf darkens, goes limp, and whatever made your kitchen smell so good a minute ago just isn't there anymore. That's why basil goes in last, off the heat, torn or sliced right before serving — let colour and aroma be your guide, not the clock.

Choose basil the way you'd choose a friend: by how alive it looks. Leaves should stand up straight, bright green, no black spots, no wilting at the stem. Smell it before you buy it — if you can't smell anything through the plastic, leave it on the shelf.

Some people say basil should go into the sauce early, so the flavour "develops." No! Give it a long simmer and you'll get a dull, tired leaf with barely any scent left — anyone who's done it knows the smell it started with never comes back. That mistake ruins many a tomato sauce — the cook adds basil at the start and wonders later why the dish smells of nothing at all.