Heat the oven to 400 degrees. Line 12 muffin cups with paper liners. Whisk the flour, sugar, baking powder and matcha powder in a large bowl. Whisk 1 cup sour cream, butter, eggs and vanilla extract in a medium bowl. Stir the wet mixture into the dry mixture. Stir in the strawberries. Spoon into the muffin cups. Bake for 20 to 25 minutes or until a toothpick inserted in the center comes out clean. Cool in the pan on a wire rack for 5 minutes. Then remove from the pan and cool completely. Meanwhile, whisk the remaining 2 tablespoons sour cream and 4 tablespoons powdered sugar in a small bowl, adding additional powdered sugar to desired consistency. Drizzle over the muffins and let stand until set. Tip: For Strawberry-Rhubarb Matcha Muffins, use 1 cup chopped strawberries and 1/2 cup sliced rhubarb and increase the sugar to 3/4 cup.