Cook potatoes in their skins until soft (20-30 min.) and let cool then mash with the olive oil and salt. You can choose to peel or leave the peel on to mix in the bread. Mix the other ingredients in a large bowl and add potatoes.

Cut the potatoes into to the flour with a spatula.

After potatoes are somewhat mixed into the flours, start kneading the potatoes in with your hands. It will be very dry at first, but after a few minutes, the moisture from the potatoes will start to bring the dough together.

When you can form the dough into a round ball, remove it from the bowl onto a floured surface. Knead for 10 minutes with the palm of your hand, continuously folding over and turning the dough. (you can use a dough mixer too)

After 10 minutes, the dough should be smooth and the potatoes mixed in very well.

Form the dough into a smooth, round ball.

Return to the bowl and cover with wrap and a towel. Place it in the refrigerator and let rise for about 9 hours or overnight.

The dough will be about double size after rising in the fridge.

Next, remove the dough onto a floured surface and cut into 8 equal pieces.

Form each piece into a round ball.

Dust each round dough ball completely with more rye flour.

Put the finished dough balls onto a baking sheet lined with baking paper. Cover with a moist towel or plastic wrap. Let the dough rise again in a warm place for about 1 hour.

Meanwhile, preheat the oven to 230°C/450°F. Place a shallow oven-safe pan at the bottom of the oven while preheating - you'll use this to create steam later! (You can skip the steam if necessary, though the crust won't come out as good).

Right before baking, bring some water to a boil on the stove (for the steam). When ready to put in the bread, cut a 1 cm slit into each dough ball. Pour the boiling water into the pan at the bottom of the stove (be careful of the steam!). Put in the bread in the middle rack.

Total bake time will be 20 minutes: Bake for 10 minutes at 230°C/450°F, then remove the steam pan. Lower the heat to 200°C/400°F and bake for another 10 minutes. Remove from oven and let cool uncovered on a wire rack.