In A Large Skillet, Saute Chicken, Onion And Cumin In Butter Until Chicken Juices Run Clear. Reduce Heat To Low. Add Pecans And Sour Cream; Cook And Stir Until Heated Through. Spoon About 1/2 Cupful Down The Center Of Each Tortilla; Top With Cheese, Salsa And Lettuce If Desired. Fold In Sides.