In a small saucpan, heat the milk and butter over medium heat until the butter melts. Allow to cool for 5-10 minutes.

In a mixing bowl add the water and milk/butter mixture and dissolve the starter and sugar (or honey if using) by mixing with a fork.

Then add the egg and mix until combined.

Lastly add the flour and salt and mix until all of the flour has absorbed the liquid. The dough will look shaggy and be sticky.

Cover the mixture with plastic wrap or a damp towel and allow it to rest for 30-45 minutes.

After the dough has rested, knead the dough for 8-10 minutes or until it comes together & is not as sticky. Try not to use too much additional flour during this process. The dough should come together nicely.

Once complete, place the dough in a greased bowl (butter or oil), cover it, and let it rest for 60 minutes.

If using a stand mixer you most likely do not need to do any stretch and folds. However, when mixing and kneading by hand I like to do a few stretch and folds to ensure the dough has optimal gluten development.

I recommend doing 2-3 stretch and folds in 60-minute increments. Once this is complete, cover the dough and allow it to rest for the remainder of the bulk rise or until doubled in size.

Once the dough has at least doubled in size, keep it covered and place it in the refrigerator overnight. You can keep the dough in the fridge for up to 24 hours.

Alternatively you can shape and bake the buns in the same day.

When ready to bake the sourdough hamburger buns, remove the dough from the refrigerator and line a baking sheet with parchment paper.

Using a food scale cut and weigh the dough into approximately eight 124-gram pieces (weigh the dough for accuracy).

Then, shape each piece into a round ball. Place the dough in your hand and scoop it under itself repetitively to tighten the seams. You can also round it out & tighten it up with the palm of your hand and a flat surface.

Place each shaped dough ball onto the baking sheet, cover with oiled plastic wrap, and allow them to rest for 2-3 hours in a warm spot.

Once the dough balls have puffed up a bit, preheat your oven to 375 degrees F and whisk together the egg and 1 teaspoon of water.

Brush each sourdough hamburger bun with the egg wash and top with sesame seeds if using.

Bake the buns for 25-30 minutes or until they turn golden brown.

Allow them to cool before cutting into them and enjoying them!

These are best eaten on the same day, but any leftovers can be stored in a bread bag or air-tight container for 3 days.

You can freeze the baked sourdough hamburger buns for up to 3 months.