Tuna Melts

Ingredients

• 4 (6-ounce) cans solid white tuna packed in water, drained
• 1/4 cup plus 1 tablespoon mayonnaise, plus more for spreading
• 1/4 cup finely chopped red onion
• 1 tablespoon plus 1 teaspoon capers, drained
• 1 tablespoon plus 1 teaspoon freshly ground black pepper
• 1 tablespoon fresh lemon juice
• 1/2 teaspoon salt
• 4 slices rustic white bread, or other dense white bread
• 2 medium tomatoes, sliced, or 8 tomato slices
• 4 ounces provolone cheese, thinly sliced