Melt 2 tablespoons margarine in small saucepan. Stir in flour; cook until bubbly, stirring constantly. Remove from heat, blend in sour cream. Return to heat, cook until bubbly and smooth; set aside. Combine eggs, tarragon, salt and pepper. Melt 2 tablespoons margarine in large skillet. Pour in eggs, cook over medium low heat. As eggs begin to set, lift cooked portions with wide spatula to allow uncooked portions to flow underneath. Cook until thickened but still moist. Remove from heat; gently stir in sour cream mixture. Spoon onto heated serving platter, garnish with parsley. Eggs will hold on a warming tray 30-60 minutes, covered with plastic wrap. Serve with choice of toppings (2-3 condiments arranged in bowls around egg dish).