Heat the oven to 350°F. Flake drained tuna into a bowl and mix with mayonnaise, celery, red onion, relish, lemon juice and pepper.
Split the connected Hawaiian rolls horizontally and place the bottom slab in a parchment-lined 9-by-13-inch pan.
Layer half the cheddar over the bread, spread tuna evenly and add remaining cheddar. Replace the top slab and brush with melted butter.
Cover with foil and bake for 15 minutes. Uncover and bake for 8 to 10 minutes until the center reaches 165°F and the cheese melts.
Rest for 5 minutes, cut into 12 sliders and serve warm.