Wash and rinse the sushi rice until the water is clear. Drain well and cook according to package instructions. Season with rice wine vinegar and cover with a damp cloth to prevent drying.

Prepare the filling by combining tuna, Sriracha sauce, sesame oil, and scallions in a bowl.

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

Roll the nori over the filling, pressing gently along the length of the roll to compact the rice and filling. Continue rolling until the far edge of the nori is sealed. Press lightly to ensure the roll is tight and compact.

Make the spicy mayo by whisking together mayonnaise, Sriracha, and lime juice in a small bowl.

For the iced matcha latte, whisk the matcha powder with hot water until smooth and foamy. Pour into a glass, stir well, sweeten if desired, and pour over ice.

Wet the blade of a sharp knife and cut each sushi roll into 6–8 pieces, cleaning the knife with a damp cloth between cuts. Top each roll with spicy mayo or serve on the side.

Serve the sushi rolls with optional wasabi, pickled ginger, a small dish of soy sauce, and the iced matcha latte.