1. Activate the Yeast (if using) and Combine Wet Ingredients: In a large mixing bowl, combine the warm milk, sugar, and sourdough starter. If using instant yeast, sprinkle it over the mixture and let it sit for 5-10 minutes until foamy. If not using yeast, simply stir the starter, milk, and sugar together. Whisk in the egg and the slightly cooled melted butter until well combined. The mixture should look milky and slightly bubbly if your starter is active.

2. Add Dry Ingredients and Form the Dough: Add the salt to the wet mixture, then gradually add the all-purpose flour, about 1 cup at a time, mixing with a wooden spoon or a stand mixer with a dough hook. Continue adding flour until a shaggy dough forms and pulls away from the sides of the bowl. The dough should still be slightly sticky but manageable.

3. Knead the Dough Until Smooth: Turn the dough out onto a lightly floured surface and knead for 5-7 minutes by hand, or 4-5 minutes with a stand mixer on medium-low speed. The dough should become smooth, elastic, and pass the “windowpane test” (where you can stretch a small piece thin enough to see light through it without tearing). If the dough is too sticky, add flour one tablespoon at a time.

4. First Rise (Bulk Fermentation): Lightly grease a clean bowl with a little oil. Place the kneaded dough in the bowl, turning it once to coat. Cover the bowl tightly with plastic wrap or a clean kitchen towel. Let the dough rise in a warm place for 1.5 to 3 hours, or until it has doubled in size. This is where the sourdough magic happens, developing flavor and airiness.

5. Shape the Dinner Rolls: Gently punch down the risen dough to release the air. Turn it out onto a lightly floured surface. Divide the dough into 12-16 equal pieces, depending on your desired roll size. Shape each piece into a smooth, round ball by cupping your hand over it and rolling it against the counter.

6. Second Rise (Proofing): Arrange the shaped rolls in a lightly greased 9×13-inch baking dish, leaving a little space between them. Cover the dish loosely with plastic wrap or a kitchen towel. Let the rolls rise again in a warm place for 45-60 minutes, or until they look puffy and have nearly doubled in size. They should be touching each other slightly.

7. Bake the Rolls: Preheat your oven to 375 F (190 C) during the last 15 minutes of the second rise. Once preheated, remove the cover from the rolls and bake for 20-25 minutes, or until they are golden brown on top and sound hollow when tapped on the bottom.

8. Finish and Serve: If desired, brush the tops of the hot rolls with 2 tablespoons of melted butter immediately after removing them from the oven. This adds a lovely shine and extra richness. Let them cool slightly in the pan before serving warm.