Gather your ingredients so that you have everything close at hand on the counter or table. Grease and flour 2 - 9" round cake pans.
Mix the Dough
In a large mixing bowl, combine sourdough starter, water, butter, granulated sugar, instant yeast and kosher salt. Add to this the instant dried milk and potato flakes.
Gradually add the all-purpose flour to the mixture. Mix together with dough hook, adding a tablespoon or two of water if necessary to make a soft, smooth dough. Knead for 4-5 minutes.
Place the dough in a lightly greased bowl and cover with plastic wrap. Allow to rise until double, 60-90 minutes.(If you opt not to use the instant yeast, you will need to go through a stretch and fold process every 40-60 minutes to activate the natural yeast in the dough. The rising process may also take 2-3 hours.)
Form and Bake the Rolls
Once the dough has doubled, transfer it to a lightly floured work surface. Gently deflate and use a bench scraper to divide the dough in half. Then divide each half into six equal pieces.
Form balls by quickly shaping the dough with your hands, starting at the top and working to the bottom, then pinching the ends together. Do this a couple of times until the ball is smooth and rounded.
Place 6 balls in each pan, evenly spacing them to give them room to rise. Cover each pan with a tea towel or plastic wrap and allow the rolls to rise until nearly doubled and puffy, about 60-90 minutes. (If using plastic wrap, be sure to spray the inside with baking spray to prevent sticking.)
Preheat oven to 350 degrees. Bake the rolls for 25-27 minutes until golden brown.
Remove from oven and spread melted butter over tops. Transfer to a wire rack to cool. Makes 12 rolls.
Notes
*Unless otherwise indicated, all butter on this site is salted.*If your sourdough starter is good and "ripened" or bubbly, you may opt not to use yeast. If you want to be certain that your rolls rise within a designated time, then you may want to use the instant yeast. Not using yeast may result in a longer rising time.