In a small bowl, whisk together rice vinegar, sugar, and salt until dissolved. Pour this mixture over your cooked sushi rice and gently mix until well combined.

Transfer the seasoned rice to a baking pan lined with plastic wrap, pressing it down firmly to form a compact layer. Cover and refrigerate for at least 4 hours or overnight.

In another bowl, combine your chopped sushi-grade salmon, Kewpie mayo, sriracha, soy sauce, scallions, and sesame oil. Mix well and chill.

Once chilled, cut the rice into 16 uniform rectangles.

Heat vegetable oil in a skillet over medium heat. Fry the rice blocks until golden brown and crispy, about 2-3 minutes per side.

On a plate, lay down your crispy rice cakes. Top with spicy salmon mixture, a slice of avocado, jalapeño slices, and sesame seeds. Serve immediately.