The vibrancy of this curry lies in the bright sourness of tamarind and the fragrant hit of fresh curry leaves, so both are worth seeking out.
1kg sweet potato, peeled and chopped into large bite-sized chunks
1½ tbsp coconut oil, warmed to liquid consistency
2 tsp ground turmeric
250g cherry tomatoes on the vine
2 tsp fenugreek seeds, coarsely crushed
2 tsp white peppercorns, coarsely crushed
1 tsp fennel seeds, coarsely crushed
1 tsp brown mustard seeds, coarsely crushed
1 cinnamon quill
12 fresh curry leaves (plus extra to serve)
1 onion, thinly sliced
2 garlic cloves, finely chopped
2 long green chillies, thinly sliced (plus extra to serve)
1 tsp dried chilli flakes
1 tsp ground coriander
2 ripe tomatoes, coarsely chopped
1½ tbsp tamarind puree softened in 2 tbsp boiling water
700ml vegetable stock or water
500ml coconut milk
steamed basmati rice
sliced green chilli
Preheat oven to 180C and line a roasting tray with baking paper.
Toss sweet potato pieces, ½ tbsp coconut oil and turmeric in a bowl until coated. Pour onto prepared tray and roast until golden (about 45 minutes). When 15 minutes remain, add the cherry tomatoes to the tray. Remove from oven and set aside.
Heat remaining tablespoon of coconut oil in a large saucepan over medium-high heat, add the crushed spices, cinnamon stick and curry leaves, and stir until spices pop (1 minute).
Add onion, garlic and green chilli and cook until tender, stirring occasionally (4 to 5 minutes).
Stir in the dried chilli flakes and ground coriander, and once fragrant, add chopped tomatoes and cook until they begin to break down (2 to 3 minutes).
Add the softened tamarind and 700ml water or vegetable stock, and simmer for 8 to 10 minutes.
Add the coconut milk and simmer for a further 4 to 5 minutes, before adding the roasted sweet potato and tomatoes. Serve with rice and garnishes of your choice.
Note: the roasted sweet potato and tomatoes should warm through in the curry, but if you prefer, you can add them earlier while it's still on the stovetop.