Heat oil on medium heat and splutter mustard and fenugreek seeds.
Add onions, serrano peppers, curry leaves and pinch of salt.
When the onions turn golden, add ginger and garlic. Stir-fry for a couple minutes and then add the spices. Mix everything together, add the water and the kodampuli.
Bring everything to a low boil and then add the salmon. After a couple minutes, gently flip the fish. After another two minutes, add the coconut milk.
Season well with salt and pepper and let the fish simmer in the coconut milk for about 5 minutes until the curry has thickened a bit.
Once the curry is done, you can cut the fish into smaller pieces with your spatula, if you’d like.