Whisk together in a medium-sized bowl, half of the soy sauce, half of the vinegar, and the sweetener. Add the chicken and toss to coat. Place in the fridge to marinate for 30 minutes.
Add oil to a skillet and heat to medium-low. Add the garlic and ginger and cook for 30 seconds, just until garlic is golden and fragrant, but not burnt.
Add the marinated chicken with any juices in the bowl and cook for 3 minutes. Add the bell pepper strips, remaining soy sauce and vinegar, and black pepper and stir. Cook for about 10 minutes until peppers have softened and chicken is cooked through.
Spoon chicken over or alongside brown rice or quinoa.
Tip: To have chicken with a crisper texture, sear on medium-high heat for 5-6 minutes, without adding the extra marinade. Add the marinade to a small pot and cook down slightly until it thickens up a touch. You might try adding a little cornstarch for a thicker marinade. Then, add to the crusted chicken and other ingredients as stated in the directions.