Sweet Potato & Black Bean Chilli

The trick is to leave the root end on while you cut — it holds the layers together so the onion does not fall apart.

1. Cut off the pointed top (not the hairy root end). Halve the onion from top to root.
2. Peel off the papery skin and the first tough layer.
3. Lay one half flat side down. Make a few cuts from top towards the root, stopping about 1 cm before it.
4. Turn the knife flat and make one or two cuts parallel to the board, again stopping short of the root.
5. Now slice across the first cuts with the claw grip. Small squares fall off. Bin the root end.

Ready when: Pieces about the size of a pea (finely chopped) or a fingernail (chopped).

Getting the seeds and white ribs out is the only fiddly part.

1. Slice off the top and bottom. Make one cut down the side and open it out flat.
2. Run the knife along the inside to cut away the white ribs and seeds.
3. Lay it skin side DOWN (the knife grips the flesh better) and cut into strips, then across for dice.

Ring-pull lids have razor-sharp edges once open.

1. Pull the ring slowly and steadily towards you, keeping fingers away from the lid's edge.
2. Don't press food down with your fingers inside an open tin — use a spoon.

Softening cooks the raw sharpness out of onions and turns them sweet. It is the start of most sauces, stews and curries.

1. Heat the oil over medium heat, add the onion and a pinch of salt (it draws out water and speeds things up).
2. Stir every minute or so. You want a gentle sizzle, not a loud fry.
3. After about 5–8 minutes the pieces go glossy, floppy and see-through at the edges. That is 'softened'.
4. Keep going another few minutes and they start turning golden — sweeter still. Only do that if the recipe says 'golden'.

Ready when: Floppy, shiny and slightly see-through, with no raw crunch when you taste a piece.

Even pieces cook evenly. Sweet potato is harder and more slippery than normal potato, so take care.

1. Scrub off any soil under the tap. Peel with a vegetable peeler, working away from you — or leave the skin on for roasting and wedges.
2. Cut a thin slice off one side so the potato sits flat and cannot roll.
3. Cut it into slabs, then the slabs into sticks, then the sticks across into cubes of the size the recipe wants.