Step 1: Cut 1 pound of beef chuck flat iron steak into ½-inch pieces; spread pieces out on a large baking pan. Add 1/4 cup butter, cut into slices, to pan. Cover and freeze for 1 hour or until partially frozen.
Grinding steak with a few pats of butter in the food processor is the only way to make unforgettable burgers.
Step 2: Heat a charcoal or gas grill for direct cooking over medium heat.
Step 3: Place partially frozen meat and butter in a food processor.
Step 4: Cover and process the meat and butter until it is coarsely ground.
Step 5: Shape ground meat mixture into four ¾-inch-thick patties. Make a small indentation in the center of each patty, which ensures the burger will cook evenly as it swells during grilling.
Step 6: Grill for 14 to 18 minutes or until done (160°F), turning once halfway through.
Step 7: Enjoy.