You are the expert at cooking burgers, ribs, even whole roasts on your gas grill, but you haven't considered giving ahi tuna a try. Ahi tuna comes from yellowfin tuna and is best served seared on the outside and rare on the inside. If you've had it and loved it a restaurant, you can enjoy it at home. The keys to ensuring a perfectly seared ahi tuna steak are a clean, hot grill and watching the steak closely when it sears so the meat is not overcooked.
Remove the tuna steaks from the refrigerator and allow them to reach room temperature, about 20 minutes.
Brush the grill grates with a pastry brush dipped in vegetable oil. Turn the grill on high, and close the lid. After 15 minutes, scrape the grill grates clean with a grill brush.
Place the tuna steaks on a clean cutting board. Coat the steaks with olive oil and a drizzle of sesame oil. Season with black pepper on both sides.
Pour the sesame seeds onto a plate or into a bowl. Coat the steaks with the sesame seeds by dipping the steaks into the seeds on the plate or in the bowl. Press down on the steaks so that the sesame seeds stick. Coat the edges of the steaks as well.
Place the steaks on the hot grill to sear for two minutes. Flip over and sear the other side for another two minutes. Watch the steaks closely so that the sesame seeds don't burn.
Using tongs, carefully sear the edges of the steaks so that all outer parts of the steaks are seared.
Remove the steaks from the grill. Allow them to rest for 15 minutes. Slice across the steaks into semi-thin strips, going against the grain. The steaks should have a rare, bright-red middle. Serve plain, with a soy-based sauce or over salad.