Chicken: Preheat your oven to 220°C fan forced. Slice 2 chicken thighs into 2cmx2cm pieces and add to a bowl with 1 egg, mixing to combine. Add 1/2 cup potato starch to another bowl, and dip each piece of chicken and remove excess starch. Evenly lay your chicken out on a lined baking tray and spray with cooking spray. Place in the oven for 20-25 minutes, flipping halfway.
Vegetables: Slice 1/4 cucumber, shred a small wedge of red cabbage and chop 1/2 baby cos lettuce. Set aside.
Sauce & Spice mix: In a bowl, combine 1/4 cup mayonnaise with 3 tbs sriracha. Set aside. In another small bowl, combine 1 tsp white pepper with 1 tsp salt, 1/2 tsp chicken stock powder, 1/2 tsp 5 spice powder and 1/2 tsp sugar.
Finish chicken: Once chicken is crispy and cooked, remove from the oven and add to a bowl with the seasoning. Toss gently to coat all pieces evenly.
Serve: Heat the bao as per packet instructions. Spread sriracha mayonnaise on the bottom, add vegetables and top with chicken & more sauce. Enjoy!