Place the buckwheat flour into a bowl and pour over boiled water. Let it rest for few minutes to cool down to a luke warm temperature.
In another bowl, mix together all-purpose flour, dry yeast and salt.
After the buckwheat flour has cooled, mix it together with dry ingredients. Knead for at least 10 minutes.
Transfer the dough back to the bowl, cover it with a kitchen towel or plastic foil, and let it rest for one hour. The dough should double in size before you continue working with it.
In the meantime, cut the walnuts into smaller pieces and quickly toast them in a pan.
When the dough is ready, knead it again and ad the toasted walnuts. The walnuts should be evenly incorporated in the dough.
Transfer the dough to a greased loaf pan, cover it with a kitchen towel and let it rest in a warm place for another 45 minutes. Preheat the oven to 410 F/210 C.
When the dough has risen properly, bake at 410 F/110 C for about 10 minutes. After that reduce the temperature to 375 F/190 C and bake for another 35 minutes until the crust looks crusty and golden.
Wrap the freshly baked bread in a kitchen towel and allow it to rest for at least about 20 minutes before you serve it. Bon apetit!