Begin by rinsing the sushi rice under cold running water. Continue rinsing until the water runs clear to remove excess starch, then drain well.
In a medium saucepan, combine the rinsed sushi rice with 1 1/2 cups of water. Bring this mixture to a boil over medium-high heat.
Once boiling, reduce the heat to low, cover the saucepan with a lid, and let it simmer for 18-20 minutes, or until the rice is tender and all the water has been absorbed.
While the rice cooks, prepare the sushi vinegar mixture. In a small bowl, whisk together the rice vinegar, sugar, and salt until the sugar and salt are fully dissolved.
After the rice is finished cooking, remove it from the heat and let it rest, covered, for an additional 10 minutes. Once rested, transfer the rice to a large bowl. While the rice is still warm, drizzle the sushi vinegar mixture over the rice. Gently fold the rice using a wooden spoon or spatula, taking care not to crush the grains. Allow the rice to cool to room temperature.
In a separate small bowl, combine the diced sushi-grade tuna with the mayonnaise and sriracha. Mix thoroughly until the tuna is well coated. Adjust the amount of sriracha based on your spice preference.
To assemble your sushi bowl, place a generous scoop of the cooled sushi rice at the base of a serving bowl.
Layer the spicy tuna mixture on top of the rice, followed by the avocado slices, thinly sliced cucumber, and cooked edamame. Finish by sprinkling sesame seeds over the top for added crunch and flavor.
Garnish your bowl with finely chopped green onions and, if desired, place strips of seaweed around the edges. Drizzle with soy sauce for an extra punch of umami flavor.
Notes
Serve in deep bowls for a visually appealing dish and use chopsticks for an authentic experience.