You can use any type of bread you like. Since I'm gluten-free, I tried out a frozen baguette from Against the Grain. It was delicious and got nice and crusty in the oven.
4large slices French breadI used bottom half of a gluten-free baguette
1tablespoonfinely chopped parsley
Instructions
Place the tuna in a medium mixing bowl. Flake into chunks with a fork. Stir in the apple, shallot, mayo, mustard, and lemon juice until the tuna is full coated in the mixture. Taste for seasoning and add salt as necessary.
Toast the bread in a 400 degree oven until lightly browned, or simply use a toaster.
Scoop the tuna on the bread slices and smooth into a thin even layer. Sprinkle with the parsley and serve.