Begin by placing your boneless, skinless chicken thighs between two sheets of plastic wrap. Using a meat mallet, pound them to an even thickness of about 1/2 inch. Season both sides with salt and pepper.

Set up a breading station with three shallow dishes. In the first dish, combine all-purpose flour with garlic powder, onion powder, and cayenne pepper. In the second, beat the large eggs until frothy, and in the third, place the panko breadcrumbs.

Take each chicken thigh and dredge it in the seasoned flour, dip it into the beaten eggs, then transfer it to the panko breadcrumbs, pressing down gently to create a thick, crunchy coating.

In a large skillet, heat vegetable oil over medium-high heat to 350°F. Fry the coated chicken thighs for about 4-5 minutes on each side until golden brown and crispy. Drain on paper towels.

In a small bowl, mix together mayonnaise, ketchup, and soy sauce until smooth. Adjust flavors to preference.

To assemble, spread sauce on the bottom half of a bun, place the chicken thigh on top, add shredded cabbage, and finish with the top bun.