Cut Ahi into 1-inch cubes. Place in a large bowl.
Add soy sauce, rice wine vinegar, sesame oil, sesame seeds (and sriracha if making spicy tuna) into bowl with Ahi and mix well. Cover and refrigerate for a minimum of 2 hours.
Serve piled high on steamed rice, quinoa, or salad leaves in a large bowl along with your favorite toppings.