Tunisian chilli paste (Harissa)

1. Wash the chillies and cut off the stems; if you want it less hot, remove some of the seeds (gloves are a good idea).

2. Roast the chillies in a dry frying pan or a 220 °C oven for 10-15 minutes until the skin is browned in patches, then leave to cool slightly.

3. Toast the coriander seeds and caraway in a dry pan for 1 minute, then grind finely in a mortar with the cumin.

4. Work the chillies, peeled garlic, spices, salt and lemon juice into a thick paste in a mortar or food processor, gradually adding half the olive oil.

5. Spoon the paste into a clean jar, smooth the top and cover with a thin layer of the remaining olive oil.

6. Store sealed in the fridge and let it mature for at least a day before using.

Tip: Harissa is Tunisia's national spice paste: it's used with couscous, in soups, with eggs and in sandwiches alike. It's traditionally made from dried chillies; if you use those, soak them in warm water for 30 minutes first. Top up the oil layer after each use and it keeps for weeks in the fridge.