In a 12-inch skillet melt margarine or butter over medium-high heat. Add chicken, mushrooms, garlic, sherry, tarragon, and lemon-pepper seasoning. Cook, uncovered for 10 to 12 minutes or till chicken is no longer pink, turning once. Remove chicken and mushrooms with a slotted spoon. In a screw-top jar combine chicken broth and flour; shake till blended. Add mixture to the skillet. Cook and stir over medium-high heat till thickened and bubbly. Remove about 1/2 cup mixture from skillet and stir into sour cream. Return to skillet along with chicken and mushrooms. Heat through (do not boil). Serve over hot cooked noodles. Garnish with lemon slices, if desired. Makes 8 main-dish servings. Nutrition information per serving: 282 cal. (27% from fat), 8 g fat, 5 7 mg chol., 25 g pro. 24 g carbo., 2 g dietary fiber, 311 mg sodium. chick 9