A new twist on an old standby.
1 (5 ounce) can solid white albacore tuna in water (such as Bumble Bee®)
1 tablespoon mayonnaise
1 tablespoon balsamic vinegar
1 tablespoon chopped onion
1 dill pickle, chopped
4 slices sourdough bread
2 slices American cheese
Mix tuna, mayonnaise, balsamic vinegar, onion, and dill pickle together in a bowl.
Spread tuna mixture over 2 slices of bread. Top with American cheese and remaining 2 slices of bread.
Cook in a panini press until bread is crispy and cheese is melted, 3 to 4 minutes.