Toast the slices of bread until they are golden brown and crispy, then set aside.
In a mixing bowl, flake the drained tuna with a fork until it’s evenly broken up and tender.
Add the capers, chopped dill, lemon zest, and lemon juice to the tuna, then drizzle with olive oil. Mix gently until combined and fragrant.
Spread the tuna mixture evenly over one slice of the toasted bread, pressing gently so it adheres well.
Top with the second slice of toasted bread to form a sandwich and press down lightly.
Slice the sandwich in half diagonally to reveal the colorful filling inside and showcase the crispy bread.
Serve immediately to enjoy the contrasting textures of crunchy bread and flavorful tuna filling.