1. In a food processor or blender, puree the red peppers and garlic with the vinegar, parsley, sugar, 3 tablespoons of the oil, 1/4 teaspoon of the salt, and 1/4 teaspoon of black pepper.
2. Light the grill or heat the broiler. Thread the shrimp on four skewers and the scallops on four skewers. Coat the shellfish with 2 teaspoons of the oil and sprinkle with 1/4 teaspoon of the salt and 1/4 teaspoon black pepper. Coat the salmon with the remaining 1 teaspoon oil and sprinkle with 1/8 teaspoon of black pepper and the remaining 1/4 teaspoon salt.
3. Grill or broil the fish, turning once, until just done, about 2 to 3 minutes per side for the shrimp, 3 to 4 minutes per side for the scallops, and 3 to 4 minutes per side for a 1-inch-thick salmon fillet (the fish should still be translucent in the center). Serve with the red-pepper sauce.
Fish Alternatives: Feel free to use only one or two types of the fish and shellfish listed. Other grilled fish that would be nice with the red-pepper sauce include halibut, swordfish, tuna, or mahimahi.
Wine Recommendation: A full-bodied, expansive wine such as a California chardonnay is ideal with the meaty, flavorful shrimp, scallops, and salmon. For the roasted red peppers and garlic, it's best to choose one that's not oaky.