Mix all grist types, except 4 tablespoons for sprinkling, yeast and salt. Add syrup, buttermilk, 200 ml hot water and sourdough. Mix everything to a soft dough. Cover and leave to rise in a warm place for about 3 hours.
Knead the seeds and seeds into the dough. Pour into a greased and buckwheat-ground box form (approx. 25 x 11 cm, 7 cm high), press it smooth and sprinkle with the remaining buckwheat grits. Cover and leave to rise in a warm place for about 1 hour.
Bake in the preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: see manufacturer) for approx. 15 minutes. Reduce the oven temperature to (electric oven: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) and continue baking for approx. 30 minutes. Remove bread from the oven, leave to rest in the pan for approx. 10 minutes, turn out and allow to cool.