Heat oil in large skillet. Saute onion until soft and golden. Add tomatoes, cook 20 minutes stirring often. In a blender, grind almonds, pine nuts, garlic, parsley and 3 tablespoons water into a paste. Stir into the tomato sauce. Cook stirring 5 minutes, if the sauce is very thick, thin with water. Season with salt and cayenne. Fold in the shrimp and heat through. Serve on a bed of rice.