Cook the rice according to its package directions. Keep covered while preparing the chicken and vegetables.
Use a separate board for raw chicken. Do not rinse it. Cut into even pieces and season with garlic powder, paprika and pepper. Wash hands and clean surfaces after contact with raw chicken.
Heat oil in a large skillet over medium-high heat. Add chicken in a single layer, working in batches if crowded. Cook for about 6–9 minutes, turning, until the centers of several of the largest pieces reach 165°F on a food thermometer. Time varies with piece size and pan heat. Transfer to a clean plate.
Add frozen vegetables and 2 tablespoons water to the skillet. Cover and cook according to the vegetable package directions, stirring occasionally and adding a splash of water if the pan dries. Cook the vegetables fully.
Return the cooked chicken and any juices to the skillet. Add 1 tablespoon soy sauce and stir until everything is hot. Divide cooked rice among four bowls and top with the chicken and vegetables. Taste before adding the remaining soy sauce.