Clean chicken thighs well. Pat dry with paper kitchen towels. Season with marinade and set aside for 30 minutes. Dip marinated chicken thighs in egg white then coat with tapioca flour.
Deep-fry in hot oil until cooked through and the chicken skin is crispy. Drain well then place on individual serving plates.
Heat oil in a saucepan and fry garlic till fragrant and almost golden. Add button mushrooms, onion and carrots.
Fry well. Add black pepper sauce and a little water. Simmer for 2?3 minutes.
Pour sauce over chicken and serve immediately.