Heat large skillet over medium-high heat; add meat and bell pepper. Cook 5 minutes, stirring until meat crumbles and is no longer pink; drain. Add taco seasoning mix and 1/2 cup water. Simmer, uncovered, 5 minutes or until sauce thickens, stirring occasionally.
Spoon 1/3 cup meat mixture down center of each tortilla; sprinkle with 2 tablespoons cheese. Roll up; place seam-side down in greased 13x9-inch baking pan. Spoon salsa over enchiladas.
Cover with foil; bake in preheated 375°F oven 18 minutes or until heated through. Uncover; sprinkle with remaining cheese. Bake 2 minutes more or until cheese is melted. Serve with lettuce, tomato, if desired, sour cream.