Blueberry Streusel Muffins
["1 3/4 c. flour", "1/2 c. sugar", "2 3/4 tsp. baking powder", "2 tsp. grated lemon rind", "3/4 tsp. salt", "1 egg, slightly beaten", "3/4 c. milk", "1/3 c. vegetable oil", "1 c. fresh or frozen blueberries, thawed and drained", "1 Tbsp. flour", "1 Tbsp. sugar", "1/4 c. sugar", "2 1/2 Tbsp. flour", "1/2 tsp. ground cinnamon", "1 1/2 Tbsp. butter or margarine"]
["Combine first five ingredients in large bowl.", "Make a well in center of mixture."]
["flour", "sugar", "baking powder", "lemon rind", "salt", "egg", "milk", "vegetable oil", "blueberries", "flour", "sugar", "sugar", "flour", "ground cinnamon", "butter"]