Whole Wheat Strawberry Cupcakes

Whole Wheat Strawberry Cupcakes - 1 cup whole wheat flour ¼ cup flax meal 1 ½ teaspoons baking powder ½ teaspoon baking soda ¼ teaspoon salt ¼ cup sugar 1 cup buttermilk ¼ cup milk 1 egg ¼ cup vegetable oil, plus more for greasing ¼ teaspoon vanilla extract 1 1/3 cup sliced strawberries, plus more for serving if you want.