Heat oil to 350°F (180ºC). Work a few wontons at a time, add to the skillet and fry on both sides, about 30 seconds total. Drain on a paper towel-lined plate.
In a medium mixing bowl whisk together the kewpie mayonnaise, rice vinegar and sriracha and set aside.
Use your fingers or two forks to shred the kani sticks and add to the bowl with the sauce.
Toss the kani in the mayo sauce then gently stir in 1 tablespoon of the tobiko (optional).
Pack ingredients in measuring cuo
Grease a 1 cup measuring cup with the oil. Add the kani salad to the cup followed by cucumber, avocado and about 1/3 cup of the cooked sushi rice. Press it firmly to pack the mixture together.
Hold a serving plate to the open side of the cup and invert it, slowly removing the measuring cup so the mixture forms a stack.
Garnish with sesame seeds, green onions and the remaining tobiko. Repeat with the remaining ingredients and serve with wonton chips.