When the starter is ready, pour more melted butter into a bowl, beat the egg, add a pinch of salt. My buns turned out not very sweet, so if you want a sweeter one, add another 3 tablespoons of sugar, a pinch of salt, pour in the sourdough. Gradually introduce the sifted flour, knead the dough. Place the dough on a work surface and knead for five minutes. It’s a little sticky, but it’s better not to add flour anymore, you can lubricate your hands with vegetable oil.