1) Preheat oven to 180C / gas mark 4.
2) Slice baguette into 1 1/4 cm-thick slices and place on a baking sheet. Bake until toasted and golden, about five to ten minutes.
3) Combine all remaining ingredients in a mixing bowl and mix thoroughly.
4) Top each toasted baguette slice with about one tablespoon of the tuna salad.