1/3 cup mayonnaise
3 tablespoons chopped fresh parsley
2 tablespoons chopped fresh chives
2 tablespoons chopped fresh tarragon
1 teaspoon minced lemon zest
2 teaspoons lemon juice
1 teaspoon Dijon mustard
1/8 teaspoon black pepper
1 (12 ounce) can solid white tuna packed in water, drained and flaked
8 (1 ounce) slices white or whole wheat bread
8 thin slices red tomato (optional)
4 (1 ounce) slices provolone cheese (optional)
Whisk together mayonnaise, parsley, chives, tarragon, lemon zest, lemon juice, Dijon mustard, and pepper in a bowl until well combined. Gently stir in the flaked tuna, cover, and refrigerate until chilled, about 30 minutes.
Spread tuna evenly over four of the bread slices. Top with tomatoes, and cheese if using, then top with remaining bread slices.