Transfer freshly cooked or warm rice to a large bowl and season with salt. Mix well. Cover with a lid and keep warm.

Open the canned tuna and strain it of its liquids using a fine sieve. In a small bowl, mix together strained canned tuna, mayonnaise, and sriracha sauce. Set aside.

Spread out a large fresh sheet of plastic wrap on a clean surface. Moisten the rice paddle or a silicone spatula with water and divide the cooked rice into four equal portions.

Scoop one portion (? cup) of the warm rice into the center of the plastic wrap. Spread out evenly into a circle, about ?-inch thick.

Divide the spicy tuna mayo mixture into four equal portions. Scoop one portion into the center of the flattened rice.

Lift and twist the corners of the plastic wrap to form a circular rice ball, gently flattening it until it?s about 1.75 inches thick. Shape it into a triangle using your thumb and pointer finger.

Remove one sheet of nori from its packaging, fold it into half to create a rectangle, and cut at the fold line to make 4 strips.

Remove the triangle rice ball from the plastic wrap and stick the rough side of a nori strip to the base of the ball starting from the middle down. Garnish with black sesame seeds and enjoy fresh!