Preheat oven to 375. Prepare eighteen 1 3/4" muffin cups with cooking spray and flour; set aside. In a mixing bowl, combine flour, half cup sugar, baking powder, salt, milk, oil, and egg. Mix until moistened. Fold in strawberries. Spoon 1/4 cup batter into each prepared cup. Bake for 12 minutes, or until edges are very light brown.