HEAT oven to 350ºF.
HEAT oil in medium skillet on medium heat. Add ham, peppers and onions; cook 5 to 7 min. or until vegetables are crisp-tender. Remove from heat. Stir in salsa. Beat eggs and sour cream with whisk until blended.
ARRANGE 6 tortilla halves on bottom of 13x9-inch baking dish sprayed with cooking spray. Spread half the vegetable mixture over tortillas; cover with half the egg mixture and 1/2 cup cheese. Repeat all layers starting with tortillas. Top with remaining tortillas. Let stand 5 min.
BAKE 25 min. Top with remaining cheese; bake 5 min. or until melted.