For the sourdough starter: In a large bowl, dissolve the yeast in the warm water. Add the flour, potato and sugar. Let the mixture rise until loose and small bubbles have formed, about an hour. Store lightly covered in a warm place until the starter takes on a sour smell and is the consistency of a bubbly pancake batter, 2 to 5 days. Use immediately or you can store it covered, in the refrigerator. To preserve the starter, feed it daily with a 1/2-inch chunk of potato.
For the biscuits: Preheat the oven to 350 degrees F and grease a 12-inch round Dutch oven with canola oil spray.
In a large bowl, add the flour and form a hollow in the center. Add the milk, oil, sourdough starter and sugar. Mix with your hands until a dough forms and begins to pull away from the sides of the bowl. You may need to add another few tablespoons of flour if the mixture is too wet. Knead the dough just until it comes together. Form the dough into a ball and cut in half. Roll out one half to a 1/4-inch thickness. Cut biscuits out using a 2-inch biscuit cutter or an empty can with the lids removed. Place the biscuits closely together in the Dutch oven. Repeat this process with the remaining dough until all the dough is used. Cover and bake until the biscuits are golden brown on top, 20 to 25 minutes.
A viewer or guest of the show, who may not be a professional cook, provided this recipe. It has not been tested for home use.