Soak the mackerel in water for about 3 hours to remove excess salt. When mackerel is finished soaking, drain and flake with a fork and set aside.

Crack open coconuts and empty juice. Grate coconut pulp into cheesecloth and squeeze out the liquid. This is the coconut milk. Discard pulp. In a medium saucepot over high heat, bring the coconut milk and water to a boil and then simmer for 5 minutes. Add the mackerel, reduce the heat to medium, and cook for 10 minutes

In another saucepot, add the vegetable oil, and heat over high heat. Add the onion, garlic, scallion, thyme, scotch bonnet, and curry powder and saute until the onions are translucent.

Add the tomato puree to the mackerel and coconut mixture and stir until well combined. Then add the onion, scallion, and thyme mixture to the mackerel and cook for another 2 minutes.

Add the seeded, diced tomato and cook for 1 minute. Season with salt and ground black pepper and serve.