10 ounces canned solid white tuna – drained and flaked
0.5 cup mayonnaise
0.25 cup celery – finely chopped
0.25 cup red onion – finely chopped
2 tbsp dill pickle – finely chopped
1 tbsp lemon juice
1 tsp Dijon mustard
0.5 tsp kosher salt
0.25 tsp ground black pepper
8 slices rye bread
8 slices cheddar cheese
4 tbsp unsalted butter – softened
Instructions
Place the canned solid white tuna in a medium bowl and flake it with a fork.
Add the mayonnaise, celery, red onion, dill pickle, lemon juice, Dijon mustard, kosher salt, and black pepper to the bowl; stir until evenly combined to make the tuna mixture.
Lay out the rye bread and spread the unsalted butter on one side of each slice.
Heat a large skillet or griddle over medium-low heat for 2 minutes.
Build 4 sandwiches: set 4 slices of bread buttered-side down in the skillet, divide the cheddar cheese between the sandwiches above and below the tuna mixture, then cap with the remaining bread, buttered-side up.
Cook until the first side is deep golden and the cheese is beginning to melt, 3–4 minutes; flip carefully and cook the second side until golden and the cheese is fully melted and the filling is warmed through, 3–4 minutes more. Reduce heat if browning too quickly and cover for the last minute if needed to finish melting.
Let rest 1 minute on a board, then cut and serve hot.