For the Berliner Knüppel mix wheat and rye flour. Add the fresh yeast and cover with salt and lard. Knead with the dough hook of the food processor to a smooth dough.
Gradually add enough water to make the dough a firm, smooth dumpling. Cover the dough and let it rise at room temperature for about 1 hour.
Now knead the dough again and form long rolls (billets). Place these buns on a floured baking sheet and let them rise, covered, for another 30 minutes.
Preheat the oven to 180 °C and bake the buns for about 15 minutes.