In 10-inch nonstick skillet heat margarine until bubbly and hot; add turkey and cook until lightly browned on both sides.
Remove from skillet and keep warm.
To same skillet add mushrooms and onion and cook, stirring occasionally, until liquid has evaporated; sprinkle with 1 teaspoon flour and cook, stirring constantly, for 1 minute.
Remove from heat.
In small bowl stir sour cream until creamy; add remaining teaspoon flour and stir to combine.
Stir 2 tablespoons vegetable mixture into sour cream mixture, then add sour cream mixture to skillet and stir to combine.
Place skillet over low heat and stir in parsley and seasonings; add turkey and cook just until heated [do not boil).