Place potatoes into TM bowl and grate 6 sec/speed 8. Scrape out and set aside in separate bowl.
Place yeast, butter and liquids into TM bowl and warm 2 min/37℃/speed 2. Add potato and allow to sit in the TM bowl until some bubbles arise and the yeast is activated. (You can use dry yeast here, 2tbsp dried yeast, same method)
Add remaining ingredients and knead 2 min/Interval.
This dough will be quite sticky, but oil a bread mat and oil your hands before handling the dough.
Scrape the dough onto prepared bread mat and form into a ball. Wrap and allow to double before proceeding. This time will vary depending on the temperature on the day you make it, do not rush it. In fact a cold rise will give you different crumb results. So for a finer crumb, a colder, slower rise is required.
When dough has risen sufficiently, shape the dough into a ball and place seam side down onto a piece of baking paper. Cover with a cloth and allow to rise again. Dredge the loaf in rye flour and then cut a few slashes in the top of the loaf.
Preheat oven at least 1 hour prior to baking. You should use the hottest oven you can get, so at least 200℃. Hotter if you can. If you are lucky enough to have a Combi Steam oven from Kleenmaid or any other brand for that matter, go ahead and use the steam function with the hottest oven possible. If you don’t have a steam oven, you can place the bread into a paper lined Varoma dish to rise. Preheat the water to boiling point (1L takes 8 minutes to reach a rolling boil) and steam 10 min/Varoma/speed 3. Place into the oven on just a rack (no tray) on the paper, and bake 20 minutes. Turn the oven down to 180℃ and bake for anywhere between 20 and 40 minutes depending on the darkness of the crust you are hoping for. The crust will thicken with longer baking as well.
Cool on a wire rack and eat in thick slices, slathered in butter.