Two 6-ounce Ahi Tuna Steaks
1/4 cup finely diced red onion
4 tablespoons extra-virgin olive oil
1 tablespoon balsamic vinegar
1 tablespoon minced basil
1/2 teaspoon crushed red pepper
Kosher salt and freshly ground pepper
4 ciabatta rolls, split
Dijon mustard and mayonnaise, for spreading
Eight 1/4-inch-thick slices of Swiss or cheddar cheese (6 ounces)
Sixteen 1/8-inch-thick lengthwise slices of kosher dill pickle
2 tablespoons unsalted butter, softened
Heat 1 tablespoon of olive oil in skillet over medium-high heat. Season both sides of tuna steaks with generous amounts of kosher salt and freshly ground black pepper. Cook tuna steaks until lightly browned on each side and cooked through, about 4-5 minutes per side. Let cool.
In a medium bowl, mix the tuna with the onion, olive oil, vinegar, basil and crushed red pepper.
Heat a panini press or griddle. Spread the cut sides of the rolls with mustard and mayonnaise and top each roll half with a slice of cheese. Spread the tuna salad on the bottoms and cover with the pickles. Close the sandwiches and spread the outsides of the rolls with the butter.
Add the sandwiches to the press and cook over moderate heat until the cheese is melted, about 6 minutes. Cut the sandwiches in half and serve.