Preheat oven to 200°C. Line a large oven tray with baking paper. Put egg and 1 tablespoon of water in a bowl and whisk until combined. Add chicken and mix until combined. Combine flour, cayenne, onion and garlic powders in a medium bowl. Season well with lots of salt and pepper.
Strain chicken from egg mixture. Add half of the chicken to flour mixture and toss until coated. Spread pieces on prepared tray. Repeat with remaining chicken. Spray with oil. Bake for about 15 minutes, turning halfway or until light golden and cooked through.
Meanwhile, to make sticky sauce; put all ingredients except lemon juice in a small saucepan over a medium heat and stir until sugar dissolves. Bring to the boil. Boil for about 3 minutes or until thickened. Remove from heat and stir in lemon juice. Set aside.
Warm tortillas on a preheated char-grill plate for 1 minute each side or in the microwave according to pack directions. Combine chicken pieces and sticky sauce in a large bowl until coated. Hold a warm tortilla in your hand. Place about 5 pieces of chicken down the centre. Sprinkle with peanuts, then top with cabbage, onion, coriander and noodles. Squeeze with lime and serve with sriracha, if desired