Surdejsrugbrød (Sourdough ryebread) is a traditional Danish kind of bread - see also Franskbrød.
The recipe is as follows (will amount to 3 breads):
Mix the ingredients and let it ferment for 3-4 days.
Let the rye-grains soften in the water for 6-7 hours. When it is ready, mix all ingredients with the sourdough and let it rise for 12-24 hours under a piece of cloth. Put the dough in tins and bake at 200°C for 75-90 minutes, but swab with water when the dough is firm.
Let the bread rest for an hour or so, and enjoy. Goes well with various kinds of sausage or spreads as openfaced coldcuts.