Step 1Place the fish in a glass dish and sprinkle with the lemon pepper and onion powder. Cover and refrigerate, about 2 hours.
Step 2Cook the garlic in the oil in a skillet over low heat just until softened and very fragrant, 2 to 3 minutes. Drain the garlic, reserving the oil. Pat the garlic onto one side of the fish filets, then pat the parsley over the garlic.
Step 3Heat 1 tablespoon of the reserved oil in a skillet over medium-high heat. Add half of the fish, garlic side down. Cook until browned, about 1 to 1 1/2 minutes. Gently turn the fish, reduce the heat to medium and cook until opaque in the center, about 3 more minutes. Repeat with the remaining fish.
Step 4To serve, place a filet on each of 6 plates, garnish with parsley sprigs and serve with one-fourth cup sauce.
Step 1Roast the bell peppers over a gas flame, turning, until the skin chars, 5 to 10 minutes. (You also can place the peppers 6 inches beneath the broiler.) Place the peppers in a bowl, cover with plastic wrap and let stand 5 minutes. Peel, seed and chop.
Step 2Combine the peppers, oil, lemon juice, garlic and salt to taste in a blender until emulsified. Makes 2 1/4 cups (save the remainder for another use).