Preheat a grill to medium high. Divide the beef into four 6-ounce portions. Gather each into a ball, then gently flatten into a 4 1/2-inch-wide patty about 3/4 inch thick. Press your thumb into the center of each patty to make a 1/2-inch-deep indentation (this prevents the patties from bulging as they cook). Season the patties on both sides with salt and pepper.
Lightly brush the grill grates with vegetable oil, then grill the patties indentation-side up until marked on the bottom, about 5 minutes. Flip and cook until marked and slightly firm, about 3 more minutes for medium doneness.
Remove the burgers to a plate and let rest 5 minutes so the juices redistribute. Serve the burgers on the buns; top as desired.