Making Spicy Tuna Sushi can be a fun and rewarding process. Follow these simple steps to create your own sushi rolls:

1. Rinse the Rice: Place the sushi rice in a bowl and rinse under cold water until the water runs clear. This removes excess starch.
2. Cook the Rice: Combine the rinsed rice and water in a rice cooker or pot. Cook according to the rice cooker instructions or bring to a boil, then reduce heat to low, cover, and simmer for 20 minutes. Turn off the heat and let it sit for 10 minutes.
3. Season the Rice: In a small saucepan, combine rice vinegar, sugar, and salt over low heat until dissolved. Pour this mixture over the cooked rice and gently fold it in with a spatula. Allow the rice to cool to room temperature.
4. Prepare the Tuna Mixture: In a bowl, combine the diced tuna, mayonnaise, and sriracha. Mix well and set aside.
5. Prepare Your Workspace: Place a bamboo sushi mat on a clean surface and cover it with plastic wrap for easy cleanup.
6. Assemble the Sushi: Place a sheet of nori, shiny side down, on the mat. Wet your hands to prevent sticking and grab a handful of sushi rice. Spread the rice evenly over the nori, leaving about 1 inch at the top edge.
7. Add Fillings: In the center of the rice, add a line of the tuna mixture, a few slices of avocado, and some cucumber sticks.
8. Roll the Sushi: Starting from the bottom, use the mat to roll the sushi tightly away from you. Make sure to pull the mat as you roll to keep the sushi tight.
9. Seal the Roll: Moisten the edge of the nori with a little water to seal the roll. Press gently to ensure it stays closed.
10. Slice the Sushi: Using a sharp knife, slice the roll into bite-sized pieces. Clean the knife with a damp cloth between cuts for cleaner slices.
11. Repeat: Repeat the process with the remaining nori sheets and fillings.
12. Serve: Arrange the sushi pieces on a platter and serve with soy sauce, pickled ginger, and wasabi.