A Finnish friend passed along a rye starter that had been given to him by a person who regularly bakes Finnish rye bread, in particular, reikaleipa (I cannot get the diacriticals to load here), a bread that is made in the shape of a donut so it can be made in batches, and stored on poles.
I could not find a sourdough recipe for the bread and my friend could only find one using yeast, so I improvised. I began with ripe starter and made a pre-ferment with that, more rye flour and water. The next day, I mixed a dough made up of the pre-ferment, more rye, water and salt. I confess, I also tossed in about a teaspoon full of vital wheat gluten, likely not too influential within the 6 lbs or so of dough that resulted.
I put the dough into the fridge overnight, removed it this morning, shaped half of it into its traditional donut, and the rest into a free-form loaf. The loaves were allowed to proof, I slashed them, then baked them on a stone with an oven temp of 400 degrees.
Much of the process is detailed in photos here:
The bread tastes great.