In a large bowl, combine ground chicken, salt, black pepper, onion powder, and garlic powder.
Form the chicken mixture into 4 circular patties, approximately 4 inches in diameter and 1/2 inch thick.
Place patties on a parchment-lined tray and freeze for 15 minutes to firm the texture for breading.
In a shallow dish, whisk together flour, paprika, chili powder, and cayenne pepper.
In a separate shallow bowl, whisk the egg and water together to create an egg wash.
Remove patties from the freezer; dredge each patty in the flour mixture, then the egg wash, and finally back into the flour mixture for a double coating.
Heat vegetable oil in a heavy-bottomed skillet or deep fryer to 350 degrees Fahrenheit.
Carefully lower patties into the oil and fry for 4 to 5 minutes per side until the exterior is golden brown and the internal temperature reaches 165 degrees Fahrenheit.
Transfer fried patties to a wire rack to drain excess oil.
Lightly toast the sesame seed buns.
Assemble the sandwiches by spreading 2 tablespoons of mayonnaise on the top bun, adding 1/4 cup shredded lettuce, and placing the chicken patty on the bottom bun.