Wash and rinse the rice until the water is clear. Drain well. Cook according to instructions on the package.

Season with rice wine vinegar. Cover with a damp cloth to prevent drying.

Prepare the Filling: Combine tuna, sriracha sauce, sesame oil, and scallions in a bowl.

Roll the Sushi: Place a sheet of nori shiny side down on a bamboo mat covered with plastic wrap. Spread sushi rice evenly on nori and sprinkle with sesame seeds. Arrange tuna mixture along the bottom edge of the nori.

Start to roll the nori over the filling and gently press along the length of the roll. This motion presses the rice and the filling together and prevents the roll from being too loose. Continue to roll the sushi until you've rolled past the far edge of the nori sheet.

Once rolled, gently press and form the length of the roll to make sure it's compact and tight.

Make the Spicy Mayo: Combine all ingredients and whisk in a bowl.

Make the Iced Matcha Latte: Whisk matcha with hot water until smooth and foamy. Pour into the glass. Stir well. Sweeten with sugar to taste. Pour over ice to serve.

Wet the blade of a sharp knife and cut each spicy tuna roll into 6 - 8 pieces. Clean the knife with a damp cloth every few cuts. Top the whole roll with spicy mayo or serve on the side.

Serve sushi rolls with an optional side of wasabi, pickled ginger, and a small dish of soy sauce for dipping. Enjoy with iced matcha latte and mochi ice cream.