Classic Tuna Salad Sandwich

1.In a medium bowl, combine the drained tuna, mayonnaise, and Dijon mustard. Mix well until creamy.

2.Add the finely chopped red onion and celery to the tuna mixture. Stir to combine evenly.

3.Add lemon juice, then season with salt and freshly ground black pepper to taste. Mix thoroughly.

4.Toast the whole grain bread slices lightly if desired, to add texture and warmth.

5.Spread the tuna salad evenly over two slices of bread.

6.Top the tuna salad with lettuce leaves and tomato slices if using, then cover with the remaining bread slices to form sandwiches.

7.Cut the sandwiches diagonally and serve immediately, or wrap for a packed meal.