Prepare a baking sheet lined with parchment and set it aside. Cut the flattened chicken into slider-sized pieces.

In one shallow bowl, whisk together the egg and water. In another bowl, combine flour with garlic powder, cayenne, coriander, salt, and black pepper. Place panko in a third bowl.

Dip each piece of chicken into the egg mixture, then coat in the seasoned flour. Return it to the egg mixture and finally coat thoroughly with panko. Arrange the coated pieces on the prepared sheet and refrigerate briefly to help the coating set.

In a small bowl, stir together mayonnaise, sweet chili sauce, hot sauce, and rice vinegar until smooth. Set aside.

Heat oil in a skillet over medium heat. Add the chilled chicken pieces carefully and cook until golden brown on one side, then turn and cook until the chicken is fully cooked and crisp on the outside. Transfer to a paper towel-lined plate to drain.

Slice the rolls horizontally and lightly toast them if desired. Spread or drizzle sauce on the bottom halves, add lettuce leaves, then place a piece of fried chicken on top. Add more sauce and cover with the top halves of the rolls.

Serve warm.