Heat the coconut oil in a frying pan over a high heat until smoking. Add the leeks, ginger and garlic and fry for 5-7 mins or until the leeks are starting to brown.
Add the curry leaves, coconut milk, tamarind paste, chilli powder, cinnamon and 1 tsp salt, and mix to combine. Reduce the heat to low-medium and cook for 45 mins or until reduced and sticky. Can be made two days ahead and kept in the fridge.