How to Make It
Halve loaf horizontally. Scoop out halves to make 1-inch bread shells. Toast shells until golden.
Combine olives, onion, capers, 2 tablespoons oil, 1 tablespoon juice, and tuna; place mixture in bottom shell. Drizzle top shell with remaining oil and juice. Top tuna mixture with lettuce, tomato, egg slices, and top shell. Wrap in plastic wrap; refrigerate 2 hours or up to overnight. Cut into quarters.