Creating the Thai Fried Chicken Sandwich is a fulfilling experience. Just follow these simple steps to achieve delicious results:

1. Marinate the Chicken: In a bowl, combine the buttermilk and chicken thighs. Cover and refrigerate for at least 30 minutes to tenderize and infuse flavor.
2. Prepare the Coating: In a separate bowl, mix together the flour, garlic powder, onion powder, paprika, cayenne pepper, salt, and black pepper.
3. Heat the Oil: In a deep skillet, heat about 2 inches of vegetable oil over medium-high heat until it reaches 350°F (175°C).
4. Coat the Chicken: Remove the chicken from the buttermilk, allowing excess to drip off. Dredge the chicken thighs in the flour mixture, ensuring they are well-coated.
5. Fry the Chicken: Carefully place the coated chicken in the hot oil. Fry for about 6-8 minutes on each side, or until golden brown and cooked through. Use a meat thermometer to ensure they reach an internal temperature of 165°F (75°C).
6. Drain Excess Oil: Once cooked, transfer the chicken to a paper towel-lined plate to drain excess oil.
7. Prepare the Buns: While the chicken cools, lightly toast the brioche buns in a separate skillet or oven until golden.
8. Assemble the Sandwich: Spread a layer of Thai sweet chili sauce on the bottom half of each bun. Place a piece of fried chicken on top.
9. Add Toppings: Pile on the shredded cabbage and garnish with fresh cilantro leaves.
10. Finish and Serve: Top with the other half of the bun and serve with lime wedges on the side for an extra burst of flavor.

These steps will guide you in creating this incredible Thai Fried Chicken Sandwich with ease and satisfaction.