HEAT oil in large nonstick skillet on medium-high heat. Add chicken; cover. Cook 4 min. on each side or until chicken is cooked through (170°F). Remove chicken from skillet; cover to keep warm.
ADD water, peas, mushrooms and soup mix to skillet; stir. Bring to boil. Stir in rice. Top with chicken; cover. Cook on low heat 5 min. Remove chicken from skillet; place on serving platter. Cover to keep warm.
STIR sour cream into rice mixture in skillet. Cook until heated through, stirring occasionally. Serve spooned over the chicken.