Heat peanut oil in a wok or large skillet. When oil begins to smoke, quickly stir in 2 cloves minced garlic, ginger root, green onions and salt. Stir fry until onion becomes translucent, about 2 minutes. Add chicken and stir until opaque, about 3 minutes. Add remaining 4 cloves minced garlic and stir. Add sweet onions, cabbage, bell pepper, peas and 1/2 cup of the broth/water and cover.
In a small bowl, mix the remaining 1/2 cup broth/water, soy sauce, sugar and cornstarch. Add sauce mixture to wok/skillet and stir until chicken and vegetables are coated with the thickened sauce. Serve immediately, over hot rice if desired.