Mix boiling water and buttermilk in a mixing bowl 

Dissolve yeast, honey, and salt in the lukewarm buttermilk.

Add rye kernels, flaxseeds, sunflower seeds, sesame seeds, and whole wheat flour, and mix everything into a thin porridge.

Now add the wheat flour and mix everything into a thick porridge.

Let the rye bread dough rest in the bowl for 60 minutes under a shower cap.

Line a rye bread pan with baking paper. Put the dough into the lined rye bread pan.

Let the rye bread rise for an additional 60 - 90 minutes under a kitchen towel.

Bake the rye bread in the middle of the oven at 180 degrees Celsius (356 degrees Fahrenheit) (fan-forced) for 1 hour and 15 minutes.

Turn the baked rye bread out onto a cooling rack and immediately remove the baking paper.

Let the rye bread cool for at least an hour.

If you prefer a softer crust on the bread, let it cool wrapped in a damp kitchen towel.