Roasting: Crisp Edges, Soft Middles

Roasting is browning in the oven. Everything in the guide to browning applies: the surface must be dry and hot before it colours, and anything crowded will steam instead.

Room on the tray

Spread vegetables in a single layer with space between them, and use two trays rather than piling one. A crowded tray gives soft, pale vegetables sitting in their own liquid.

Metal trays brown better than glass or ceramic dishes, and dark metal better than shiny.

Cut for the heat

Cut pieces the same size so they cook together. Vegetables that take longer (potatoes, carrots, beetroot) go in first or smaller; quick ones (courgettes, peppers, tomatoes) go in later or larger.

Flat cut faces against the tray brown best, so halve sprouts and cut squash into wedges.

Potatoes

Floury potatoes such as Maris Piper and King Edward make the crunchiest roast potatoes; their outsides break down into a crust. Waxy ones stay smooth.

Parboil them in salted water until the edges are soft, let them steam dry for a few minutes, then shake them in the colander to rough up the outsides. That ragged surface is what becomes the crunch.

Put them into fat that is already shimmering hot. Goose fat, dripping and rapeseed oil all take a high heat. Parboiled potatoes left uncovered in the fridge overnight dry out and roast crisper still.

Oil, salt and finishing

Toss vegetables in just enough oil to coat them; more makes them greasy rather than crisp.

Delicate herbs and garlic burn in a long roast. Add chopped garlic and soft herbs such as rosemary for the last 10 minutes, or roast whole unpeeled cloves, which steam gently in their skins.

Turn things once, not constantly, and finish with salt as they come out.