Dry-fry the cumin and coriander seeds in a small, heavy-based frying pan over a medium heat for 2–3 minutes until they emit a nutty aroma, then grind them to a powder in a mortar with a pestle.
Drain the chillies, chop off the stalks, and squeeze out most of the seeds.
Discard the stalks and seeds and coarsely chop the chillies.
Using a mortar and pestle, pound the chillies with the garlic and salt to form a thick, smooth paste.
Add the ground spices to the paste and pound again, then beat in most of the oil.
Spoon the paste into a sterilized jar and pour over the remaining oil.
Seal the jar and store in a cool place or in the refrigerator.
Use within 2 months.
Notes / Tips / Wine Advice:
For pickled red chillies,
pour 400 ml white wine or cider vinegar into a saucepan with 2 tablespoons sugar, 2 teaspoons sea salt and 2 teaspoons coriander seeds. Bring the vinegar to the boil, stirring until the sugar has dissolved, then turn off the heat. Using a small sharp knife, slit 8 red guajillo or serrano chillies down one side, from the stalk to the tip, making sure you don’t cut right through them. Pack the chillies in a sterilized jar and pour the vinegar mixture over the chillies to cover completely. Seal the jar and store in the refrigerator for at least 2 weeks before using. Store in a cool place and use within 4–6 months. Serve whole as a starter or slice finely and scatter over salads, tagines or couscous.