Buttermilk Sweet Potato Biscuits

Heat the oven to 400 degrees F.

Stir the flour, baking soda, baking powder, and salt with a fork in a mixing bowl.

Drop in the butter and toss it in the flour, then cut it into pieces. Work the butter into the flour until it resembles oatmeal.

Whip the sweet potato with a fork until it's very smooth, then add it to the bowl. Work it in lightly but thoroughly with your fingers. Add 1/2 cup of the buttermilk and stir. Add just enough additional buttermilk to make a smooth and only slightly sticky dough.

Dump the dough onto a floured surface and knead it two or three times. Flatten it out to 1/2 inch thick, you can dirty a rolling pin for this if you want, but your hands will do the job just fine and cut out biscuits with a 2 1/2-inch cutter.

Put the biscuits on a baking sheet. Gather the scraps together, pat it down, and cut out more biscuits.

Brush the biscuits with buttermilk and bake for about 15 minutes, until well risen and appealingly browned. Serve hot.