Combine flour and butter by mixing with your hands until it resembles course cornmeal.
Mix sweet potatoes into dough.
Add buttermilk and mix well.
Turn out dough onto a floured surface. Sprinkle flour on top. Knead 10 to 12 times. Roll to 1/2 inches thick. Cut with a 2-inch biscuit cutter (or cup or glass or jar, whatever you can get your hands on).
Place biscuits, once inch apart on a baking sheet that’s been prepared by greasing or covering with a baking mat. Brush tops of biscuits with oil.
Bake at 450 degrees for 12 to 15 minutes or until tops are golden brown.