Tuna Panini Melt

Ingredients (7)

• + 1 (5 ounce) can solid white albacore tuna in water (such as Bumble Bee®) add to pantry
• + 1 tablespoon mayonnaise add to pantry
• + 1 tablespoon balsamic vinegar add to pantry
• + 1 tablespoon chopped onion add to pantry
• + 1 dill pickle, chopped add to pantry
• ✓ 4 slices sourdough bread
• + 2 slices American cheese add to pantry