Place the rye grain into a coffee grinder and blitz until coarsely ground.
Pour the cracked rye into a large bowl with the mixed seeds and pour over the water. Set aside to soak overnight or for at least six hours.
When the seeds have soaked and your starter is looking bubbly, pour the starter into the seeds and stir to combine.
Then add the dark rye flour and salt and stir well. The mixture will be quite dense but you should be able to stir it without much resistance.
Line a 12x21cm loaf tin with parchment paper.
Scrape the dough into the tin and use the back of a wet spoon to smooth down the surface.
Place inside a plastic bag and set aside to rise for about 6 hours.
Once it reaches the top of the loaf tin put it into the refrigerator to rest overnight.
The next day, preheat your oven to 250°C or as high as it will go.
Place the bread into the oven and bake for 30 minutes. Then turn it down to 220°C and let it bake for a further 20 minutes.
Remove from the tin and allow to cool. Once it has reached room temperature place the bread into a plastic bag and seal. Set aside to rest for 1 day before slicing.
