Season chicken with salt and pepper. In rondo, heat canola oil over medium heat. Brown chicken on skin side only; remove from pan. Drain excess oil from pan; add ginger and garlic. Cook for 2 minutes, stirring occasionally. Return chicken to pan; add stock, soy sauce, vinegar, sugar, oyster sauce and cayenne pepper. Bring to a simmer; cover and cook in 325 degree oven 45 minutes.
While chicken is cooking, in saute pan, heat sesame oil over medium heat. Brown sausage on all sides; add mushrooms and saute until lightly browned. Add green onions; saute for 1 minute. After chicken has cooked 45 minutes, add sausage mixture; cook, uncovered, 30 minutes more. Just before serving, adjust seasoning; add bok choy. Serve over rice.