Step 1

Heat the 120ml (1/2 cup) oil in a large casserole pan over a medium heat.

Step 2

Add the onions and cook, stirring occasionally for 20 minutes, until they start to brown and caramelise slightly.

Step 3

Add the 8 cloves of garlic, 2 tbsp minced ginger, 2 tbsp garam masala, 2 tbsp coriander, 1 tbsp cumin, 1 tbsp paprika, 1 ½ tsp turmeric, 1 tsp cinnamon, 2 tsp salt, 1 tsp black pepper, ¼ tsp ground cardamom and 2 tbsp tomato puree.

Step 4

Stir to coat the onion and cook for a further 5 minutes, stirring often.

Step 5

Add the red pepper, green pepper, carrot, tinned tomatoes and stock.

Step 6

Bring to the boil, then simmer for 1 hour.

Step 7

Turn off the heat, allow to cool, then blitz to a smooth liquid using a stick blender.