- 4 cans (5 ounces each) solid white tuna packed in water, drained
- 1/3 cup mayonnaise, plus more for spreading
- 1/4 cup finely chopped red onion
- 4 teaspoons capers, drained
- 1 Tablespoon fresh lemon juice
- 1/2 teaspoon coarse salt
- 1 teaspoon ground pepper
- 1/4 teaspoon dried oregano leaves
- 6 slices crusty bread
- 10 thin slices tomato
- 6 slices provolone
In a medium bowl, combine tuna, mayonnaise, onion, capers, lemon juice, salt, pepper and oregano and stir thoroughly until combined.
Arrange bread on a baking sheet and spread a little mayonnaise on each slice. Divide tuna salad evenly among slices, then top each with 2 slices tomato and 1 slice of cheese.
Heat broiler, with rack in highest position. Broil until cheese is golden brown and bubbling, 3 to 4 minutes.