Whisk together the rice vinegar, sugar, and salt in a small bowl until dissolved. Pour this mixture over your cooked sushi rice, gently folding to combine.

Spread the seasoned rice in a pan lined with plastic wrap, pressing it down firmly. Cover and refrigerate for at least 4 hours, or overnight for best results.

In a separate mixing bowl, chop your sushi-grade salmon and combine it with Kewpie mayo, sriracha, soy sauce, scallions, and sesame oil. Stir well, then cover and refrigerate.

Once the rice has chilled, cut it into 16 rectangles. Heat vegetable oil in a skillet over medium heat.

Fry the rice rectangles until golden brown on both sides, about 3-4 minutes per side. Drain on paper towels.

On each crispy rice rectangle, layer a slice of avocado, a tablespoon of the spicy salmon mix, and jalapeño slices. Finish with black and white sesame seeds.