- 4 (1-inch-thick) slices of crusty bread cut from a wide, round loaf
- Extra-virgin olive oil (EVOO), for liberal drizzling
- 1 clove garlic, smashed and peeled
- 3 (8 ounce) tuna steaks, cut into large chunks
- 3 sprigs rosemary, leaves stripped and finely chopped
- 1 tablespoon grill seasoning, such as McCormick's Montreal Steak Seasoning
- 2 teaspoons orange zest
- 1 navel orange, peeled and thinly sliced crosswise
- 1 teaspoon Worcestershire sauce
- 2 teaspoons aged balsamic vinegar (eyeball it)
- 4 slices red onion
- 8 slices fontina cheese
- 2 cups shredded radicchio, arugula or baby spinach
- Salt and freshly ground pepper
- Preheat a grill or a grill pan to medium-high. Drizzle the bread with EVOO and grill until toasted, 1 to 2 minutes on each side. Rub the garlic all over.
- Place the tuna in a food processor and pulse until ground. Transfer the tuna to a bowl and add the rosemary, grill seasoning, orange zest, Worcestershire sauce and vinegar and a liberal drizzle of EVOO.
- Brush the onion slices with EVOO and grill them until tender, 3 to 4 minutes on each side.
- While the onions cook, ready the burgers to go on the grill by forming 4 large patties. Grill the patties with the lid down for 2 minutes on each side for rare and up to 5 minutes on each side for well-done. A minute before taking the burgers off the grill, top with an onion slice and 2 slices of cheese. Place the grilled bread on a platter, top with the orange slices, radicchio and burgers. Season with salt and pepper and enjoy!