Peel and clean prawns, dice into small chunks about 1/4-inch along with scallops and rock shrimp. Place into mixing bowl, add half the amount of tomatoes, also half amount of basil. Except for the capers, add remaining ingredients, mix well and set aside. Place casing in a sausage stuffer machine and make sausages about 6 inches in length. Blanch in simmering water, do not over cook.
Heat olive oil in a hot skillet. Brown both sides and cook through. Place each sausage in a serving bowl (1 per person), and serve with the remaining diced tomato, basil, and capers poured over the sausage.