Step 1: Prepare your grill for two-zone cooking. For charcoal, pile coals to one side. For gas, turn one or two burners to high and leave adjacent burners off or low. Aim for 500-600°F (260-315°C) in the direct heat zone.
Step 2: Remove the Wagyu steak from the refrigerator 30-60 minutes before grilling to bring it closer to room temperature. Pat the steak thoroughly dry with paper towels. Season generously on all sides with coarse sea salt and freshly ground black pepper.
Step 3: Place the seasoned Wagyu steak directly over the high-heat zone. Sear for 2-3 minutes per side, developing a dark brown crust. Watch for flare-ups; if they occur, briefly move the steak to the indirect zone until they subside.
Step 4: Once seared, move the steak to the indirect heat zone. Close the grill lid and cook, flipping occasionally, until it reaches your desired internal temperature (e.g., 125-130°F / 52-54°C for medium-rare). Use a meat thermometer to ensure accuracy.
Step 5: Remove the steak from the grill and place it on a cutting board or warm plate. Tent loosely with foil and let it rest for 10-15 minutes. This allows the juices to redistribute, resulting in a more tender and flavorful steak.
Step 6: Slice the rested Wagyu steak against the grain into ½-inch thick pieces. Serve immediately and savor the rich, buttery flavor and melt-in-your-mouth texture.