1. Heat oven to 400 degrees . Lightly coat a large baking sheet with nonstick cooking spray.
2. In a large bowl, whisk together flour, cornmeal, baking soda, cream of tartar and salt. In a small bowl, combine sour cream, egg and sugar. Make a well in dry ingredients and add sour cream mixture. Blend until dry ingredients are moistened. Knead 6 times in bowl.
3. Drop 1/2-cup mounds of batter onto prepared baking sheet. Bake at 400 degrees for 14 to 15 minutes, or until a wooden pick inserted in center comes out clean. Remove biscuits to a wire rack to cool completely.Topping
4. Combine mascarpone cheese, sugar and milk. Stir until smooth.Filling
5. Combine strawberries and sugar.
6. To serve, split biscuits and fill with strawberries. Top with mascarpone mixture.