Blueberry Lemon Muffins

1 3/4 cups flour
1/4 cup sugar
2 1/2 tsp baking powder
3/4 tsp salt
1 egg, beaten
1/3 cup vegetable or canola oil
3/4 cup milk
1 cup blueberries, fresh or frozen
1 to 2 tsp grated lemon rind
2 Tbs. or more butter, melted
1/4 cup sugar

Preheat oven to 400 degrees. Grease 12 muffin cups or fill with papers. Spoon flour into measuring cups and level with a knife. Put measured flour in a mixing bowl and stir in 1/4 cup sugar, baking powder and salt. Beat egg in a separate bowl with oil and milk. Add flour mixture to egg mixture until just moistened. Fold blueberries and lemon rind gently into batter. Fill prepared muffin cups two thirds full. Bake 20 to 25 minutes, until muffins are done. While still warm invert muffins and dip tops into melted butter and remaining 1/4 cup sugar. Makes 12 muffins.