How to Make It
Combine flour and 1/2 teaspoon salt in a medium bowl. Place beaten egg in a second bowl. Place panko in a third bowl. Working in batches, dredge squid in flour mixture, dip in egg, and dredge in panko, shaking off excess.
Heat 2 inches of oil in a large saucepan over medium-high to 350°F. Working in batches, fry squid until golden brown, about 3 minutes. Drain on paper towels, and season with salt to taste.
Spread Serrano-Lemon Aioli on top halves of rolls. Place avocado, chicharrones, lettuce, cucumber, and calamari on bottom halves of rolls. Drizzle with Key Lime Ponzu. Cover with tops of rolls.