Start by combining oyster sauce, sesame oil, lemon juice, garlic, salt, and pepper in a bowl. Mix well until everything is evenly blended. This marinade creates a bold and balanced flavor for the salmon.
Place the salmon fillets in a baking dish and coat them evenly with the marinade. Bake in a preheated oven at 430°F (220°C) for about 20 minutes. The salmon should be tender, flaky, and lightly caramelized.
While the salmon bakes, cook the vermicelli noodles according to package instructions. Rinse them under cool water and drain well. Wash and dry the lettuce and mint leaves so they are ready for assembly.
Dip each rice paper wrapper into warm water until it becomes soft and flexible. Lay it flat on a clean surface. Add lettuce, noodles, mint, and flakes of baked salmon in the center. Fold the sides inward and roll tightly to seal.