1. Take the butter out of the fridge and let it sit at room temperature for about 1 hour before using, so that it will become soft enough to spread.
113 g Butter
2. In a large bowl, combine the milk, eggs, honey, and sourdough starter. Mix until well combined.
100 g Milk
3 Eggs
30 g Honey
150 Active Sourdough Starter
3. Stir in the flour and salt, then mix until a dough forms.
450 g Bread Flour
10 g Salt
4. Turn the dough onto a lightly floured surface. Knead for 10 minutes, or until smooth and elastic. Add more flour or milk if necessary. Cover and let rest for 20 minutes.
5. Add the butter in two stages. Add half of the butter and knead until well incorporated. The dough may fall apart, but it will become smooth once the butter is incorporated. A dough scraper can be helpful in this step. Cover the dough and let it rest for 20 minutes.
6. Add the rest of the butter, and knead until the dough is smooth and elastic. Cover the dough with plastic wrap, and let it rest for 10 minutes at room temperature.
7. To know if your dough is ready for the next step, perform the windowpane test. Stretch a small piece of dough until it is thin enough to see light through it. If it stretches without tearing, it is ready for the next step. If the dough tears, it needs to be kneaded more. Knead it for a few more minutes, then let it rest for 5 minutes and repeat the test. Continue kneading and resting until the dough is ready.
8. Bulk fermentation*: Transfer the dough to a greased bowl, cover it, and let it rise in a warm place until doubled in size. This could take anywhere from 4 to 12 hours, depending on the room temperature.
9. Chill the dough for at least 1 hour for easier shaping. It can be refrigerated for up to 24 hours. I leave mine overnight.
10. Divide the dough into 7 equal pieces and knead each portion of dough into a ball. Then, roll each ball into a flattened dough about 12 cm long and 10 cm wide / 5 inches long and 4 inches wide. After that, tightly roll up the dough to form a cylinder and tuck in the sides, then pinch the edges to seal. If the dough is sticky, you can lightly flour the work surface to make it easier to handle.
11. Spread some cooking oil on the baking pan. Place the dough rolls on the prepared baking pan and press down gently to flatten them slightly.
12. Proofing*: Cover with plastic wrap or a tea towel, and let the buns rise in a warm place for 2 to 4 hours, or until soft and light to the touch.
13. Preheat the oven to 350°F / 180°C.
14. Mix one egg and one tablespoon of water. This will create an egg wash. Lightly brush the tops of the buns with the egg wash.
15. Bake for 30 to 40 minutes, or until the buns are golden brown and the internal temperature reaches at least 190°F / 88°C.
16. Allow the buns to cool completely before slicing them.
Enjoy!