Best-ever Tea Biscuits

2 cups all-purpose flour, sifted
2 Tbsp. sugar
1 Tbsp. baking powder
1/2 tsp. baking soda
1/2 tsp. salt
3 Tbsp. cold butter (NOT margerine)
1 egg
1 cup dairy sour cream
Set oven to 450 degrees F. Grease a cookie sheet and dust with a little flour. Sift the dry ingredients together, then cut the butter into the dry mixture until butter is in tiny but separate bits. Beat the egg lightly and add sour cream. Pour this mixture into dry ingredients and stir briefly with a fork. Gather dough into a ball, put onto a well-floured board or counter. Pat out to about 3/4 inch thick (do not roll the dough - this will make it tough). Cut rounds (about 2, 1/2 " diameter) and place them on floured cookie sheet. If using for shortcake, dust tops with granulated sugar. Bake for 10 to 15 minutes, or until golden brown.