1Preheat oven to 350°F. Heat oil in large skillet. Add peppers and onion to skillet; cook and stir 5 minutes or until tender-crisp. Transfer mixture to large bowl. Add chicken, 1 cup of the cheese and mayonnaise; toss gently to coat.
2Spread 1/4 cup of the salsa in bottom of 13x9-inch baking dish. Spoon 1/2 cup of the chicken mixture down the center of each tortilla. Fold over tortilla sides; place seam-side down in baking dish. Spread remaining salsa over enchiladas. Sprinkle with remaining 1 cup cheese. Cover with foil.
3Bake 20 minutes or until sauce is bubbly and cheese is melted. Sprinkle with cilantro and serve with sour cream, if desired.