For the Granita: Place juice in a metal bowl, Cover bowl with plastic wrap or a top if it has one and place in the freezer. Freeze for 4 hours. Remove from freezer and stir well with a fork (to break up the ice and give it a grainy texture). Place back in the freezer and stir it again with a fork every 30 minutes for the next two hours. It should be ready after about 6 hours total freezing time, but is best if stirred regularly until ready to serve. For the Poke: Pat the Ahi tuna dry, then neatly cut it into small 1/4 inch cubes. Place in a bowl. Add soy sauce, sesame oil, and sesame seeds. Gently toss. In a Asian spoon, place 1 tablespoon of the Granita and top with a half of teaspoon of poke, garnishing with sliced green onion. Recipe crafted by: Chef Carlo Cavallo