No Milk Brioche

This is my favourite brioche recipe at the moment. 

for 18 to 20 rolls
600g flour (half strength)
280gr sourdough
200g soy milk
90g coconut butter
90g sugar
grated rind of half a lemon untreated
2 eggs
1tsp salt

* jam for the filling

I usually start this recipe at night.
Dissolve the yeast in the soy milk and set aside.
Pour the flour in a bowl (or use a planetary mixer), drill a hole in the centre and pour in the natural yeast, starting to mix, then the sugar and eggs. Once the dough is formed add the coconut butter and eventually the salt.
Mix well and long, until the dough does not come off on your hands or the sides of the bowl of the mixer (adjust if necessary add a little milk and a little flour depending on whether the mixture is present too dry or too sticky).
Let rise overnight, or until the dough has doubled.
In the morning  roll out the dough to a thickness of 2 cm then cut into squares of side about 6-8 cm from the side, and place on each square a teaspoon of the filling chosen (or nothing at all, they are very good even simple ), and then join the corners of the square, so as to form the bundles  and put the buns next to one another with "legs down", ie with the smooth part and bulging (and buttered) above.
Let rise until doubled in volume (for 4  hours), then bake in a preheated oven at 200 ° C for 20 -25 minutes, until they are golden brown.