Drain the tuna thoroughly. Open the cans, press the lid down to squeeze out excess liquid, and transfer to a mixing bowl. The drier the tuna, the better the texture.

Make the creamy base. In a small bowl, whisk together Greek yogurt, mayonnaise, dijon, the zest of half a lemon, and 1–2 teaspoons of lemon juice. Start with less lemon juice and add more to taste.

Prep the crunch. Finely chop celery, red onion, and pickles. Aim for even, small pieces so they blend well without big chunks.

Combine. Add the creamy base and chopped veggies to the tuna. Sprinkle in chopped herbs if using, plus a pinch of red pepper flakes.

Season. Add a pinch of salt and several grinds of black pepper. Mix gently with a fork to keep some flake in the tuna rather than mashing it smooth. Taste and adjust lemon, salt, and pepper.

Toast the bread (optional but recommended). Lightly brush slices with olive oil or a thin layer of butter and toast until golden. This adds crunch and keeps the bread from getting soggy.

Layer the sandwich. Add lettuce to the bottom slice to act as a moisture barrier. Pile on a generous scoop of tuna salad. Add tomato slices if you like, then top with the second slice of bread.

Slice and serve. Cut in half for easier eating. Serve with crunchy veggies, chips, or fruit on the side.