In a mixing bowl, combine the flour, sourdough discard, egg, milk (or water), salt, sugar, and add them to the mixer with the hook attachment. 2 ¼ cups Unbleached All-Purpose Flour, 1 cup Sourdough Starter, 1 egg, ¼ cup milk or water, 1 teaspoons salt, 1 tablespoon sugar

Mix all the ingredients for about 5 minutes until the dough is sticky and cohesive.

Gradually add the cubed butter and increase the mixer speed to achieve a smooth and shiny dough. Test the dough with the windowpane test, where you stretch a piece of dough until you can see through it.3 tablespoons unsalted butter

After mixing, dump the dough onto a lightly floured surface. Gently stretch and fold until a smooth round ball forms that is able to keep its shape.

Cover the dough in a bowl and let it rest in a warm place for approximately 3 hours, allowing it to ferment and rise at least 50%.

After it's risen by at least half, degas the dough by punching the center or slowly allowing it to fall out of the bowl. Dump it out onto a lightly floured surface and divide into 6-8 equal balls.

Be sure there are no gas bubbles in each ball as you begin to shape them. Use some traditional sourdough techniques to build tension within each ball. Gently pushing the dough up from the side and then towards you from the top is a great way to build tension and produce a fluffy texture.

Place them on a greased or parchment-lined baking sheet or a hamburger bun pan.

Cover the buns with plastic and let them rise until they double in size, which should take about 90 minutes.

Preheat your oven to 190°C or 375°F, approximately 30 minutes before baking.

Once the buns have proofed, brush the tops with the beaten egg and sprinkle with toppings like sesame or poppy seeds if desired.

Bake the buns for 18-20 minutes or until they achieve a light golden brown color.

Remove the buns from the oven and cool them on a rack before serving.

Store your sourdough hamburger buns in a bag for up to 5 days, or freeze them for up to 30 days, ensuring you can enjoy homemade buns whenever you desire.