Let butter sit at room temperature to soften if using it.
In a medium bowl, combine tuna, mayo, shallot, celery or scallion, pickle, salt, pepper, and lemon juice.
Spread butter or mayo on one side of each bread slice.
Flip two slices over and layer each with cheese, tomato, and half the tuna salad.
Close sandwiches with the remaining slices, buttered side up.
Heat a skillet over medium-low. Grill each sandwich 3–4 minutes per side, pressing lightly, until golden brown and cheese is melted.
P id=”instruction-step-7″>7. Cut in half and serve immediately.
