Cut the boneless skinless chicken breast into cubes. Mix the cornstarch and 1Tbs shoyu. Blend with chicken. Set aside. Mix the other 2 Tbs of shoyu, sherry, sugar and vinegar. Set aside. Heat 3Tbs of oil in a skillet, add chicken and chili peppers. Saute for 2 minutes and set aside. Next, saute green onions and ginger for one minute, then put the chicken back into the pan. Cook for 3 minutes. Add shoyu mixture from a previous step and cook until done (a couple of minutes.)