Fry the garlic and ginger, chillies, bay leaves and salt in the ghee or oil for 2 minutes then add in the onions.
Cook over low to medium heat for 40 minutes until the onions are golden and sticky, adding a splash of water if they start to catch on the bottom of the pan.
Add in the spices, tomato purée and tinned tomatoes then add enough water to just cover the vegetables.
Pop on the lid and simmer for 30 minutes.
Leave to cool then blend until smooth using either a food processor or a stick blender.
Portion into 300g amounts and store in the fridge for 3 to 4 days or 3 months in the freezer.
