Tuna Burgers with Tapenade

Name: Tuna Burgers with Tapenade
Ingredients: 4 (6-inch long) pieces of baguette bread, halved horizontally; 1/3 cup pitted green olives; 1/4 cup pitted kalamata olives; 1 tablespoon drained capers; 1 tablespoon plus 2 teaspoons extra-virgin olive oil; 1 tablespoon fresh lemon juice; 1 tablespoon fresh Italian parsley leaves; 1 teaspoon lemon zest; 1 anchovy, minced; Salt and freshly ground black pepper; 1 (12 to 14-ounce) tuna steak; 1/3 cup mayonnaise; 2 tablespoons Dijon mustard; 1/2 cup purchased roasted bell peppers, drained and sliced into 1/2-inch wide strips; 4 thin slices red onion; 4 romaine lettuce leaves