I'll post a sourdough recipe later.
Mix the milk, yeast and sugar.
Incorporate the flour gradually.
Add the salt and knead the dough for 15 minutes.
Let the dough rest for 2 hours.
Remove air from the dough and stretch it to form the bread.
Let the dough rest in the refrigerator for 24 hours (covered with a cloth and flour bottom not to stick)
Bake in the oven (250 Celsius) for 10 minutes and lower the temperature to 200 degrees for 40 minutes.
Leave in the oven (10 or 15 minutes) with the door open to create a crispy crust.