Start by combining the water, milk, sourdough starter, coconut oil, sugar, and melted butter. Whisk until combined.
Whisk the bread flour and salt together until combined.
Add the wet ingredients to the dry ingredients, and knead with your hands until the flour is moistened. The dough will be shaggy.
Let the dough rest for 10-30 minutes.
After the rest, knead the dough for around 10 minutes. It should be smooth and springy.
Shape the dough into a ball and place it in a glass dish, and cover with a damp towel for 1 hour.
At this point you can begin a series of fold and stretches. Starting on one side stretch the dough and fold it over itself to the middle. Continue this stretch and fold all the way around the dough. Repeat the process every 10 minutes for a total of 5 rounds.
Cover the dough with a damp towel and let it rise. This time will vary depending on the temperature of your kitchen. The dough should double in size in around 6-12 hours.
After the bulk rise, turn the dough out onto a floured surface. Divide the dough in half for easier molding.
Flatten the dough to about 1 1/2 inches thick with your hands. Divide the dough into 12 equal squares using a pizza cutter. You could also use a scale and weigh each piece if you wanted to be precise.
Mold each piece into a round ball by gathering the corners together, and lightly rolling the dough on the surface of the counter.
Place the rolls on a cookie sheet lined with parchment to rise the second time. Second rise can take 2-4 hours, again, depending on the temperature of your kitchen.
Bake the rolls in a pre-heated 350° F oven for 30 minutes until they are golden brown. Top them with melted butter immediately after removing them from the oven. Serve warm.
