In the bowl of a stand mixer, add the warm milk, sourdough starter, bread flour, butter, salt, honey, eggs and egg yolk (save the egg white for the egg wash at the end) and knead with the dough hook attachment. Knead for 15 minutes or until the dough passes the windowpane test. Perform the windowpane test by pulling a piece of dough thin enough to see light through without it tearing. It will be a weaker windowpane. If it doesn’t pass, continue to knead for another couple minutes.200 grams milk, heated to 100 degrees, 180 grams active sourdough starter, 550 grams bread flour, 60 grams butter, softened, 10 grams salt, 45 grams honey , 45 grams honey , 1 egg yolk
Place the dough on a lightly floured work-surface and knead into a ball. Place the dough ball in a bowl or straight edge container to rise covered at 80°F. Let rise for about 4-5 hours or until doubled in size.
Punch down the dough and divide into 10 (110 gram) balls. Roll into circles on a lightly floured work surface.
Place on two baking sheets lined with parchment paper, 5 on each. Press down with the palm of your hand so they flatten to about 3.5”-4” wide.
Let them rise covered for another 2-3 hours in a warm spot until puffy and well-risen. When you poke the side, the indent should stay. Mix egg white and water and brush the top of the buns with it. Sprinkle with sesame seeds. 1 egg white, 2 Tablespoons sesame seeds, 2 Tablespoons sesame seeds
Bake in a preheated 375℉ oven for 20 minutes. To serve, slice with a serrated knife and add your favorite burger toppings.
Notes
Let the dough double for the first rise in a warm spot to speed up the process.
After several minutes in the mixer, if the dough is super sticky, add a little more flour until it is just a little tacky.
You can make 12 smaller buns instead of 10 if preferred.
If your buns puff up dramatically in the oven or come out pale, it's a sign they needed a longer rise before baking. For beautifully browned, evenly baked buns, be sure to let them get puffy and well-risen before they go in the oven.
To store the sourdough hamburger buns, let them cool completely and then store them in an airtight container or ziplock bag for up to 4 days on the counter.
To freeze, let the buns cool completely, and then add them to a freezer bag and freeze for up to 3 months. To thaw, remove them from the freezer and let them defrost on the counter.