Prepare the dipping sauce. In a medium mixing bowl, combine the soy sauce, rice vinegar, and honey until the honey dissolves. Whisk in the sesame oil, ginger, and garlic until smooth. If desired, leave at room temperature or refrigerate. (Note #1 on the recipe)

Preheat a gas (or charcoal) grill to high heat. (Note #2 on the recipe)

Rinse and pat dry tuna steaks with paper towels. Rub olive oil on all sides of the tuna and season with salt and pepper. Grill the tuna for 2 minutes per side, or until the outside is seared and the center is rare. (If you want a cooked center, cook for an additional 2 minutes on each side.)  Place the tuna on a cutting board. Thinly slice tuna across the grain with a thin, sharp knife (14 to 12 inch thick slices). Sprinkle with sesame seeds and green onion slices. With dipping sauce, serve.