In a medium bowl, whisk together ¼ cup of rice vinegar, 2 tablespoons of sugar, and 1 teaspoon of salt until fully dissolved. Gently fold this mixture into the cooked sushi rice until thoroughly combined.

Transfer the seasoned rice into a lined baking pan, pressing down gently to form an even layer. Cover the pan with plastic wrap and chill the rice in the refrigerator for at least 4 hours, or ideally overnight.

Chop 1 pound of sushi-grade salmon into small pieces. In a bowl, mix the salmon with 4 tablespoons of Kewpie mayo, 2 tablespoons of sriracha, 2 teaspoons of soy sauce, 2 tablespoons of minced scallions, and 2 teaspoons of sesame oil.

Remove the chilled rice from the refrigerator and cut it into 16 equal rectangles. Heat ½ cup of vegetable oil in a large skillet over medium heat until shimmering. Fry the rice rectangles until golden brown and crispy, about 3-4 minutes per side.

Assemble by placing a slice of avocado on each rice rectangle, adding the salmon mixture on top, and garnishing with jalapeño and sesame seeds. Serve immediately.