Prepare fish: Clean the fish and pat dry with paper towel. Season with salt and pepper and mix well to coat. Set aside.
Cook aromatics: Heat oil over medium flame. Add diced onions and cook until translucent. Add minced garlic, grated ginger, dried thyme, and half of the curry powder. Cook for about one minute while stirring constantly to prevent burning.
Add tomato base: Add diced tomatoes and tomato paste. Stir and cook for another 1 to 2 minutes.
Add coconut milk and spices: Stir in half of the coconut milk. Add minced habanero pepper, bouillon powder, and salt. Add sliced bell peppers, mix well, cover, and leave to come to a boil.
Finish sauce and cook fish: Add the remaining half tablespoon of curry powder and the remaining coconut milk. Mix well. Gently place the seasoned fish into the sauce and cook until tender.
Serve: Once fish is cooked through and tender, serve hot. Optionally garnish with chopped scallion stalks.