1. For the Herb Mayonnaise, combine basil, dill, or tarragon; mayonnaise; 1 teaspoon lemon juice; 1/4 teaspoon pepper and shallot in small bowl. Set aside.
2. With narrow knife, slice salmon diagonally into 1/4-inch-thick slices. Combine maple syrup and 4 teaspoons lemon juice in cup.
3. Spread Herb Mayonnaise on one side of each slice toasted bread. Brush syrup mixture on both sides of salmon; sprinkle with salt and pepper to taste.
4. Heat 1 teaspoon of the oil in large nonstick skillet over high heat until very hot. Cook half the salmon slices until opaque, 30 to 45 seconds per side. Remove to plate. Repeat process cooking remaining slices with remaining 1 teaspoon oil.
5. Layer each of 4 slices toast, mayonnaise-sides up, with salmon and a lettuce leaf, then a second slice of toast, sliced tomato, and 2 slices of bacon. Cover with third slice toast, mayonnaise-side down. Makes 4 servings.