Ingredients
* 1 small white onion, sliced into 1/4-inch rings
* 1/2 cup fresh orange juice (from 2 oranges)
* 1/4 cup fresh lime juice (from 2 to 4 limes)
* 1/4 teaspoon ground cumin
* 2 garlic cloves, crushed
* 1 1/2 pounds flank steak, trimmed of excess fat
* Coarse salt and freshly ground pepper, to taste
* 2 tablespoons unsalted butter, room temperature
* 1 loaf ciabatta (16 inches), split horizontally, halved crosswise
* 6 ounces Gruyere cheese, thinly sliced
* 1 whole dill pickle, thinly sliced crosswise
Directions
Combine onion, juices, cumin, and garlic in a shallow dish. Add steak, and let stand, turning once, for 20 minutes.
Preheat a grill pan to medium-high and oven to 400 degrees. Pat steak dry, and season with salt and pepper. Grill to desired doneness, 5 to 6 minutes per side for medium-rare. Let rest.
Grill onion for 2 to 3 minutes.
Discard marinade.Butter bread. Grill, buttered side down, for 2 minutes. Place cheese on bottom halves, and bake in oven until melted. Slice steak thinly, against the grain. Top cheese with pickle, steak, onion, and bread. Halve each sandwich, and serve.
