Step 1: Pat the chicken thighs dry with paper towels. Trim any excess fat. For even cooking, you can gently flatten thicker parts of the chicken.
Step 2: In a medium bowl, whisk together the hoisin sauce, honey, soy sauce, Shaoxing wine (if using), Chinese five-spice powder, minced garlic, grated ginger, and red fermented bean curd (or red food coloring if using). This creates your vibrant Char Siu marinade.
Step 3: Place the chicken thighs in a large resealable plastic bag or a shallow dish. Pour the marinade over the chicken, ensuring each piece is thoroughly coated. Seal the bag or cover the dish and marinate at room temperature for at least 15-30 minutes, or refrigerate for up to 4 hours for deeper flavor. Do not marinate longer than 4 hours for chicken.
Step 4: When ready to cook, preheat your broiler to high with a rack about 6-8 inches from the heat, or preheat your air fryer to 375°F (190°C), or oven to 400°F (200°C). Line a baking sheet with foil and place a wire rack on top (for broiler/oven methods).
Step 5: Remove chicken from marinade, letting excess drip off. Discard any remaining marinade that touched raw chicken. If you want extra glaze for basting, set aside 2 tablespoons of the initial marinade before adding chicken.
Step 6: For Broiler: Place chicken on the wire rack. Broil for 5-7 minutes per side, or until deeply browned and cooked through. During the last 2-3 minutes, brush with fresh glaze (honey + hoisin mix) or reserved marinade (that did not touch raw chicken) for extra shine and flavor. Watch carefully to prevent burning.
Step 7: For Air Fryer: Arrange chicken in a single layer in the air fryer basket. Cook for 12-18 minutes, flipping halfway, until an internal temperature of 165°F (74°C) is reached. Brush with glaze during the last few minutes.
Step 8: For Oven: Place chicken on the wire rack on the baking sheet. Roast for 20-25 minutes, flipping halfway, until cooked through. Brush with glaze during the last 5-7 minutes.
Step 9: Once cooked, remove the chicken from the heat and let it rest on a cutting board for 5 minutes before slicing. This helps keep the chicken juicy. Slice against the grain into desired pieces and serve immediately.