Roast the coriander, cumin and fennel seeds in a dry pan for a couple of minutes until fragrant. Tip spice mix into a blender and grind to a fine powder, then transfer to a bowl. Add the garlic, onion, chillies, red pepper and olive oil to the blender and blitz to a paste.
Tip paste into a shallow pan and cook for 15 mins until it reaches a jammy consistency, stirring constantly towards the end. Stir in the spices and 1.5 tsp salt, then remove from heat.
