2 cups unbleached all purpose flour
1 tablespoon sugar
1 tablespoon cornstarch
2 teaspoons baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1/4 cup (1/2 stick) chilled unsalted butter, cut into 1/2-inch pieces
3/4 cup chilled buttermilk

Preheat oven to 450 F. Sift first 6 ingredients into large bowl. Add butter and rub in with fingertips until mixture resembles coarse meal. Add buttermilk and stir until dough forms.

Turn dough out onto floured surface; knead until smooth, about 8 turns. Roll out dough to 1-inch thickness. Using 2-inch-diameter biscuit cutter or cookie cutter, cut out biscuits. Gather scraps; roll out to 1-inch thickness and cut out additional biscuits.

Transfer biscuits to large ungreased baking sheet. Bake until golden, about 12 minutes. Serve warm.