Cream margarine and sugar until light and fluffy.
Beat in egg, milk and vanilla until nearly smooth. Stir 1 3/4 cups flour, baking powder and salt into mixture.
Mix just until dry ingredients are moistened; batter will be lumpy.
Toss blueberries with 1 tablespoon flour to coat and fold into batter.
Spoon into 12 muffin cups. Bake at 425° for 25 minutes or until evenly browned.