Combine salt, 1/2 tsp turmeric, 1tsp cumin, and 1 tsp of coriander and season both side of each fillet with the mix. Allow to rest for 10 minutes.
Simmer coconut milk with habanero, red pepper flakes and lemongrass for 10 minutes to infuse the flavors. Set aside.
Over medium heat, saute the onion, garlic, and remaining turmeric in oil. When slightly browned (about 8 minutes) add tomatoes. Saute for another five minutes, or until tomatoes have begun to make a thick sauce.
Add coconut milk and stock, and simmer for 1 minute. Very gently drop in fish, cover and simmer for 3 minutes on each side. Garnish with cilatro and serve.