A well-marbled rib-eye is so rich and flavorful on its own that it requires nothing more than salt, pepper, and fire. Build a two-zone fire so you can sear it over hot embers then finish cooking slowly over medium-low heat to develop a crispy, crunchy steakhouse crust and a juicy interior. If you're working with a boneless rib-eye, lessen the cooking time by a few minutes.
Put the steak on a wire rack set on a rimmed baking sheet. Pat dry with paper towels. Season with ½ teaspoon of the kosher salt per side. Let stand at room temperature for at least 1 hour.
Pat dry with paper towels. Season again with ½ teaspoon salt per side. Press in ½ teaspoon cracked peppercorns per side so pieces adhere.
Build a two-zone medium-hot/medium-low fire in a charcoal grill, or heat a gas grill on high just before cooking, leaving 1 burner on low. Brush the grill grate with oil. Sear the steak over higher heat, flipping once, until nicely charred, 3-4 minutes per side.
Using tongs, lift the steak and sear both edges (the bone side and the fat-cap side) for 1-2 minutes per side to render out some of the fat. Grill the steak to the desired temperature, 14-18 minutes total or until an instant-read thermometer registers 120 degrees for rare (the steak will carry over to 125 degrees, or medium-rare, as it rests.)
Transfer the steak to a work surface and let rest for 10 minutes. Slice against the grain, and season with coarse sea salt, to taste.