Cook steaks as directed on package. Cut into strips and set aside. Spray 1 side of tortilla with cooking spray; place sprayed side down in 10-inch nonstick skillet. Layer with the cooked chicken and shredded cheese. Top with another tortilla; spray top of tortilla with cooking spray.
Cook uncovered over medium heat 4 to 6 minutes, carefully turning after 2 minutes, until golden brown. Repeat with remaining tortillas, chicken mixture and cheese. Cut into wedges, and serve with sour cream and, if desired, salsa.