Put whole wheat flour, salt, sugar, and dry yeast in a bowl and mix.
Add warm water and milk, then knead the dough.
Add butter to the dough and knead again until smooth.
Cover the dough with plastic wrap and let it rise for the first fermentation.
Divide the dough into 6 pieces and form into balls.
Roll out each piece into a triangle shape and roll it up like a log.
Lightly brush the bread with water and sprinkle with coarse salt.
Place on a baking tray lined with parchment paper and let it rise for the second fermentation.
Bake in a preheated oven at 180°C for 18-20 minutes.