Sprinkle the yeast over the water in a small bowl. Set aside.
Combine the rye flour with plain flour in a large bowl. Stir in the salt. Mix in the yeast mixture to make a soft dough. Turn dough out onto a board floured with rye meal. Knead lightly, mixing in rye flour as needed. Shape dough into a fat roll and cut into 12 sections. Roll each section into a ball; cover balls with a towel and let rise 20 minutes.
Preheat oven to 220 degrees C. Lightly grease 2 baking trays.
On a floured board roll out each ball into a flat round about 10cm in diameter. Place rounds on prepared baking trays and prick with a fork.
Bake in preheated oven until lightly browned, 8 to 10 minutes. Cool on a rack.