Heat a wide pan over a medium heat and add a splash of oil. Throw in the cumin, mustard and fenugreek seeds (leave the ground fenugreek until later if using).
When the seeds start to pop add the garlic, ginger, curry leaves if using and onions.
Cook gently for 10-15 mins or until the onions turn soft and golden.
Add the lime zest, ground coriander, turmeric, ground fenugreek (if using), half the chili and after a few seconds, the tomatoes.
Cook gently for 10 mins so you have a paste, then add 2 tablespoons of water and the coconut milk.
Bring to the boil, add the shrimp and simmer for 5 mins until they are cooked.
Season with sea salt, add the lime juice, transfer to bowls and sprinkle over the remaining chili and cilantro leaves.
Serve.
