Mix flour, sourdough starter, water and salt into a soft dough. Cover and let rest for 1 hour.
Stretch and fold the dough 2 times: the first time after around 2 hours of fermentation and the second time after around 8 hours.
Allow the dough to ferment slowly for a total of 24 hours in a cool place.
Divide dough into portions and shape into buns.
For the savory version, mix in butter and honey during shaping.
For the sweet version, incorporate cranberries, butter, soy milk and sugar.
Preheat oven to 200 °C and bake buns for about 18–20 minutes until golden.