Place the rice in a fine mesh strainer and rinse until the water that runs out of the bottom is clear. In a medium saucepan, combine the rice and 2 cups (400g) water.
Cover and cook on low heat for 20 minutes. Remove from the heat, sprinkle with mirin and fluff the rice with a fork and let cool. (This can also be done in a rice cooker)
Line a loaf pan with plastic wrap, then spread the sushi rice evenly, pressing it down so that it is tightly packed. Transfer to the refrigerator for at least an hour.
Lift the plastic wrap from the pan, then use a knife to cut it into 8 even squares.
Heat the vegetable oil in a skillet to 375°F (190ºC). Fry only a few squares of rice at a time in the pan. Cook, rotating so that the rice is golden brown on all sides, about 3 to 4 minutes.
Remove from the pan to a paper towel-lined plate to drain. Cut each square of crispy rice in half.
Heat a large sauté pan over medium heat, add the oil and heat. Add the shrimp, cooking until pink and no longer translucent, about 1 min. Flip and continue to cook until just cooked through.
Remove to a cutting board and allow to cool completely. Finely chop the shrimp then add to a bowl with the green onions, breadcrumbs, mayonnaise, sriracha, jalapeño and soy. Stir to combine.
Top each piece of crispy rice with a slice of avocado and a scoop of the shrimp salad. Drizzle with eel sauce and top with jalapeño.
Serve immediately with soy sauce for dipping.