Cook and season the sushi rice with sushi vinegar, then let it cool to room temperature.
In a bowl, whisk together the flour, cornstarch, and enough water to make a smooth slurry.
Place the panko breadcrumbs in a separate bowl.
Lay a nori sheet on a clean surface and spread an even layer of sushi rice over it.
Roll it tightly into a long log, sealing the edge with a little flour slurry if needed.
Dip the entire sushi roll into the flour slurry, then coat evenly with the panko breadcrumbs.
Heat oil to 350°F (175°C) and fry until golden brown and crispy on all sides.
Transfer to a paper towel-lined plate and let it cool for 2–3 minutes.
Using a sharp knife, carefully slice the crispy roll lengthwise down the center, like a hot dog bun, without cutting all the way through.
Spread cream cheese inside, then fill with thinly sliced cucumber, avocado, and sashimi-grade salmon.
Drizzle generously with sriracha mayo and eel sauce, then finish with a sprinkle of furikake.
Serve immediately while the outside is hot and crispy and the filling stays cool and fresh.
