In a large bowl, combine together the medium rye flou with the white whole wheat flour.
Make a well in the flour and add the yeast, the warm water and the sugar.
Mix well to combine, cover with a towel and let it rest in a warm place for around 2 hours.
Add 600 ml water, caraway and salt to the starter dough.
Knead all the ingredients well and bring it to a smooth dough. Knead for around 15 minutes.
Make a ball with the dough. Cover and let it rest for around 2 hours.
Shape the dough. Place on a lined baking dish.
Brush with warm water and sprinkle with some wheat flour.
Bake on a previously pre-heated oven at 200° C.
After 20 minutes reduce the temperature to 180°C and bake for 40 minutes more or until done.