Put the fish in a large nonreactive mixing bowl along with the lime juice and set aside for 20 minutes.
Heat a large saute pan over medium-high heat. Add the dende/olive oil to the pan, and once hot, add the onions and saute, stirring often until translucent, about 3 to 4 minutes. Add the minced garlic to the pan and saute for an additional 30 seconds. Add the tomato paste, chopped tomatoes, fish stock and 1 teaspoon of the salt to the pan and stir well to incorporate. Bring to a boil, and add the fish with the lime juice, as well as the Piri Piri, and the coconut milk; stir to combine.
Once the liquid comes to a boil, dot the top of the pan with the sliced tomatoes and cover with a lid. Reduce the heat to medium-low and continue to cook until the flesh starts to flake, about 10 minutes. Remove the cover and sprinkle the cilantro over the fish. Season with the remaining salt, if needed. Serve with the rice.
Heat a small saute pan over medium-high heat. Add 1 tablespoon of the olive oil to the pan. Once the oil is hot, add the garlic and peppers to the pan. Saute, stirring often, until the edges of the garlic start to turn brown, 3 to 4 minutes. Add the lemon juice and remove from the heat.
Place the contents of the saute pan into a blender and add the salt. Puree the peppers and garlic until mostly smooth. With the motor running, drizzle the remaining 1/2 cup of olive oil through the feed tube of the lid of the blender. Let cool before using, and store refrigerated in an airtight container.