Add the dark beer and let it soak into the dough. Then add honey, rye kernels, flaxseed, sunflower seeds, and sesame seeds.
Mix well and set aside 300 grams in the fridge for the next time you bake. It can last about 4 weeks and doesn't need to be fed.
Divide the rest of the dough into 2 equal-sized bread pans (lined with parchment paper to prevent burning) and let it rise for a couple of hours at room temperature. Again, make sure to cover with a kitchen towel.
Then smooth the surface and place it in a cold oven. Set the oven to 200 degrees Celsius (392 degrees Fahrenheit) (fan) and bake for 1 hour and 15 minutes.
Remove the bread and place it on a rack to cool. Once cooled, dampen two kitchen towels and wrap the bread in them. We usually let it sit overnight before placing it in bags, with one of the loaves going into the freezer.