Combine Ingredients: Mix half water and half milk, then add sourdough starter, salt, sugar, yeast, and malt extract. Stir to homogenize before adding flour.
Handmixing + Autolysis: After stirring in the butter, add the flour and mix by hand to start the autolysis process. Let sit for 15 minutes to develop gluten strength.
Bench Knead: Knead the dough on the bench until soft, without adding extra flour.
Prepare Butter: Shape 200 grams of butter into a rectangle using parchment paper, then freeze to harden.
Roll Out Dough and Add Butter: Roll out the dough and place the frozen butter in the center. Enclose the butter with the dough like a letter.
First Fold: Perform the first fold to create 4 layers, then let the dough rest in the fridge for an hour.
Second Fold: Roll out the dough again and perform a second fold to achieve 8 layers.
Third Fold: Perform a third fold to reach 32 layers, then let the dough rest in the fridge.
Shape Croissants: Roll out the dough into a rectangle, cut into triangles, and roll each triangle into a croissant shape.
Proof: Let the croissants proof until doubled in size, which may take longer due to the cold dough.
Egg Wash and Bake: Apply egg wash for color, then bake in a preheated oven at 200 degrees Celsius with steam created by boiling water in a tray for optimal crust development.