Cut into 2" strips. Marinate in a wasabi, ginger vinagrette, sesame seed oil, oyster sauce, and soy sauce mixture for 2 to 3 hrs. Remove from mixture and cover all sides with fresh cracked pepper. High heat sear on the grill, about 30 seconds a side. In a bowl, mix some wasabi mayo (HEB sushi bar), ginger, a little oyster sauce and sesame oil, and soy sauce. Cut tuna into 3/8" slices and dip into sauce. Enjoy.