How to Make It
In a bowl, toss the meat with 1/2 teaspoon salt. Cover with plastic and refrigerate overnight.
Coarsely grind the meat in a grinder and shape into 1 1/4-inch-thick patties; work quickly so that the meal remains chilled.
Light a grill or heat a grill pan or a cast-iron skillet. Season the burgers with salt and pepper and grill or pan-fry over moderately high heat, turning once, about 4 minutes per side for medium-rare or until done to your liking. Let rest for 2 minutes, then serve with the focaccia with the tomato and red onion.