Sourdough starter:
Dissolve the yeast in warm water, mix all ingredients well, cover with a moist cloth and leave to rest in a warm place (30 °C) for 1 hour.
Completion:
Knead the sourdough with all ingredients to form soft dough; place in a bowl, cover with a damp cloth and leave to rise for 15-20 min. Dust the dough with rye flour, divide into 10 pieces of similar size, form small or medium size rolls and arrange on an oven tray covered with baking paper, allow to swell for 30-40 min, then bake in a preheated oven at 230 °C for approx. 45 min.