Prep Time: 25
Cook Time: 5
Serves: Serves: 2
Cook onion with honey and vinegar in a large nonstick skillet over medium-low heat 20 minutes or until tender, stirring occasionally. Season with salt and freshly ground black pepper to taste.
Preheat panini pan or heat gas grill to medium-low.
Slice off the tops of the ciabatta. Split the rolls horizontally in half. Turn bottom halves up and top each with 2 slices of cheese, onion relish, salami, tomato slices and remaining 4 slices cheese. Close sandwiches with top halves of ciabatta rolls. Brush lightly with olive oil, if desired.
Cook sandwiches in preheated panini maker or on gas grill for 4 to 5 minutes, turning once, until cheese is melted and bread is golden brown.