Put a frying pan on a medium to high heat and add the cumin and coriander seeds for toasting to the dry pan. Lightly toast them for a few minutes until golden brown and smelling delicious, then remove the pan from the heat.
Add the toasted spices to a pestle and mortar and grind until fine, or put them into a food processor and whiz to a powder.
When you've ground them whiz the toasted spices in a food processor with the rest of the ingredients until you have a smooth paste. Add a little more tomato puree if more liquid is needed;.
Stated the recipe should store well in the refrigerator kept in a small airtight container. Cover the paste is a layer of oil to keep it fresh.