In the bowl of a standing mixer, combine the warm water and the yeast. Stir and then let the yeast sit for 10 minutes to proof.
Add the sourdough starter and stir until well incorporated.
In a separate bowl, whisk together the flour, sugar, and salt.
Add the flour mixture to the yeast mixture and the vegetable oil to the standing mixer bowl.
On a low setting, use the dough hook of the standing mixer to knead everything together. Continue to mix until the dough pulls away from and cleans the sides of the bowl.
Turn out the dough onto a lightly greased surface and shape into a round.
Place round in a lightly greased container with a lid. Let dough rest until double in size, about 45 minutes to 1 hour depending on kitchen temperature.
Turn dough out onto lightly greased surface and punch down. Divide the dough into 24 pieces and shape into balls. Each ball should weigh about 80 grams.
Place dough balls onto a greased baking sheet. Cover and let rest for 30 to 45 minutes until double.
Preheat the oven to 400° Fahrenheit (204° Celsius) and bake for 16 to 18 minutes.
Brush with melted butter and serve warm.