Place the rice in a fine mesh strainer and rinse until the water that runs out of the bottom is clear. This gets some of the starch out of the rice. In a medium saucepan, combine the rice, 2 cups of water, mirin and rice vinegar. Cover and cook on low heat for 20 minutes. Remove from the heat and fluff the rice with a fork.
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.
Finely chop the tuna. While it can be chopped using a knife, the easiest way to do this is by using the pulse mode on a blender or food processor.
In a medium bowl mix the tuna, mayonnaise and chili sauce. Stir in the green onions and hot sesame oil. Cover and refrigerate until ready to use.
Heat the vegetable oil in a skillet to 375°F (190ºC). Lift the plastic wrap from the pan of rice, then use a knife to cut it into 8 even squares.
Fry only a few pieces of rice at a time in the pan. Cook the rice patties, rotating so that the rice is golden brown on all sides, about 3 to 4 minutes. Remove from the pan and place on a paper towel-lined plate.
Place each crispy rice on top of a leaf of butter lettuce (optional). Top each of the pieces of fried rice with a tablespoon size of the spicy tuna mixture. Top each crispy rice and spicy tuna with a slice of avocado, a slice of jalapeño and drizzle with eel sauce. Serve immediately.
Video
Notes
Pack the rice tightly so it holds together when fried. Use plastic wrap to help shape it into balls or press it evenly into a lined quarter sheet or 9x9-inch pan. Once cooled, cut into equal rectangles for perfectly portioned crispy rice pieces.