HEAT oven to 350°F.
HEAT oil in large skillet on medium-high heat. Add vegetables; cook and stir 5 min. Stir in chicken. Add water and seasoning mix; stir. Cook 10 min., stirring occasionally. Stir in sour cream.
PLACE half the chips in 13x9-inch baking dish; cover with layers of half each of the chicken mixture and cheese. Repeat layers.
BAKE 20 min. or until heated through.