Source: Adapted from Martha Stewart
2 cans of chicken, drained (12 oz each)
1/3 cup mayonnaise, plus more for spreading
1/4 cup finely chopped red onion
4 teaspoons capers, rinsed and drained
1 tablespoon fresh lemon juice
1/2 teaspoon coarse salt
1 teaspoon ground pepper
1/4 teaspoon dried oregano, crumbled between your fingers
4 slices crusty bread
8 thin slices tomato
4 slices provolone
1. Heat broiler, with rack in highest position.Place bread on a baking sheet and broil for 3-4 minutes, or until lightly toasted. Remove from over.
2. In a medium bowl, combine chicken, mayonnaise, onion, capers, lemon juice, salt, pepper, and oregano and stir until thoroughly combined.
3. Spread a little mayonnaise on each slice of toasted bread. Divide tuna salad evenly among slices, then top each with 2 slices tomato and 1 slice cheese. Broil until cheese is golden brown and bubbling, 3 to 4 minutes.