Dissolve the yeast in warm water, mix well with the flour, keep stirring for 5 min., then knead vigorously for further 5 min. Cover with cheesecloth and leave in a warm place (30 °C) for 1 hour.
Mix the sourdough with the other ingredients to form a soft dough; dust with rye flour and leave for 10-15 min. Divide into 10 pieces of similar size and form small rolls - 80-100 g, arrange on an oven tray covered with baking paper either in pairs or singly, allow to swell for 30-45 min, then bake in a pre-heated oven at 220° C for approx. 45 min.