Place the chicken cubes in a large bowl and add garlic powder, salt, and black pepper. Cover and place in refrigerator. Combine the soy sauce, dark soy sauce, water, white vinegar, lemon juice, and sugar in a bowl and set aside.
Heat a 4-quart saucepot or clay pot over low heat. Add brown candy pieces or brown sugar and melt slowly over medium heat, stirring frequently to avoid sticking and burning. When sugar comes to a slow boil, carefully add fish sauce. Add the soy sauce mixture, Thai chile, garlic, and ginger. Add chicken to the liquid and cook, stirring occasionally, until chicken is tender, about 8 minutes.