Mix together yogurt, 100 ml water, yeast, 1 tsp salt and 100g rye flour.
Leave the dough covered for two days on the kitchen table.
Dissolve the sour dough in 1 liter of water in a large bowl.
Add 2 tablespoons of salt, chopped rye seeds and 600g of rye flour, and mix the mixture into a smooth dough.
Cover the dough with a damp tea towel and let it rest on the kitchen table for a day.
Add the beer, syrup, linseed, kernels and 500g of rye flour to the batter and stir.
Take 300g sourdough and keep in a container with a tight lid for the next baking. The dough lasts about 3 weeks.
Grease two loaf tins with butter and add the dough.
Cover the dough with a damp tea towel and let it rest on the kitchen table for 2 hours.
Heat the oven to 100 degrees.
Brush the surface with a little water and bake the loaves on the lowest setting for 1 hour. Increase the heat to 175 degrees and bake the bread for another two hours.
Cover with aluminum foil if it starts to look too dark.
Leave the loaves to cool for half an hour before placing the breads from the molds on a wire rack for further cooling.