If the usipa is dried, soak it in water for about 30 minutes to rehydrate. Drain and set aside.
In a large skillet or pan, heat the vegetable oil over medium heat. Add the chopped onion and cook until soft and translucent, about 5 minutes. Stir in the minced garlic and cook for another minute.
Add the diced tomatoes to the pan. Cook until they break down and become saucy, about 5-7 minutes. Stir in the paprika, ground coriander, and cayenne pepper (if using). Season with salt and black pepper to taste.
Gently fold the usipa into the tomato mixture. Cook for an additional 5-10 minutes, stirring occasionally, until the fish is cooked through and well-coated with the sauce.
Garnish with fresh coriander or parsley if desired. Serve hot with nsima, rice, or as a side dish.
Enjoy your meal!