Defrost the prawns if necessary. Rinse anchovies, dab dry and chop very finely. Peel onion and garlic and chop finely. Heat 1 tbsp. oil in a wide saucepan. Sauté the anchovies, onion and garlic.
Briefly sauté the tomato paste. Add the tomatoes and juice, chop coarsely and bring to the boil. Season with salt, pepper and 1 pinch of sugar. Simmer open for about 15 minutes.
Cut olives smaller. Wash basil, shake dry, pluck leaves and cut into fine strips. Rinse fish, dab dry and cut into larger pieces. Season with salt and pepper.
Stir the olives, capers and basil into the tomato sauce and season again. Put the fish on the sauce and let it simmer covered for 6-8 minutes.
Cut the prawns in the back and remove the dark intestine. Rinse shrimps and pat dry. Heat 2 tablespoons of oil in a frying pan. Fry the prawns for 2-3 minutes. Season with salt and pepper and also add to the tomato sauce.
If you don't want to eat low-carbohydrate, eat ciabatta with it.