In a mixing bowl, stir all tuna salad ingredients until mixed thoroughly.
10 ounces tuna, drained, ⅓ cup mayonnaise, 2 teaspoons dijon mustard, 1 stalk celery, 1 lemon, 1 teaspoon kosher salt, ½ teaspoon black pepper, 2 teaspoons Old Bay seasoning
Spread the butter on one side of each slice of bread. Assemble each sandwich with a portion of the tuna salad, a slice of tomato and two slices of cheese. The buttered side of the bread should be facing out.
8 slices thick sliced bread, 4 Tablespoons butter, 8 slices cheddar cheese, 4 tomato slices
In a large skillet, heat the vegetable oil over medium high heat. Once the pan is hot, add 2 of the sandwiches. Heat until bread is golden brown and cheese is melted, about 2 to 3 minutes per side. Repeat with the remaining two sandwiches.
1 Tablespoon vegetable oil