Dissolve the sourdough starter in 4 cups of lukewarm water. Then add 500g freshly ground whole wheat flour, 500g freshly ground rye flour, 75g freshly ground flaxseed and 3 Tbsp salt. Finally, add the grain mixture from day 1. Mix it all together and let it sit covered for 24 hours.
Spray your loaf pans with oil. Divide the dough into the pans. Cover them and let them rise for 3-4 hours.
Preheat the oven to 395F and bake for 1.5 hours. Once they are done, remove them from the pans and let them cool on a rack.