Put the chicken in a large mixing bowl. Add the ground black pepper and fish sauce. Mix well and let it stay for 1 hour.
Meanwhile, combine the flour and cornstarch in a large container. Mix well.
Heat a deep cooking pot. Pour-oil and then let the oil get hot enough to fry.
Dredge the marinated chicken in the flour and cornstarch mixture.
Deep fry for 12 minutes per side (medium heat); flip to cook the other side for 8 to 10 minutes
Transfer to a serving plate. Serve hot.
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