Heat a wok or heavy-based frying pan and, without adding any oil, dry-roast the cumin and coriander seeds for 40–50 seconds until they are toasted and aromatic. Tip into a spice grinder and grind to a powder.
Put the powder in a food processor with all the other ingredients and whiz to a fine paste (add a little water if the mixture is too stiff). Store in a jar i