Greek Yogurt Tuna Salad Sandwich

Steps

1. Drain the tuna and flake it into a bowl.
2. Mix in the Greek yogurt, mustard, finely diced celery, salt, pepper and a squeeze of lemon.
3. Toast the bread if you like and add the lettuce and tomato slices.
4. Pile on the tuna salad, close the sandwich and cut it in half.