Mix the poolish/levain:

1. The evening before you plan to bake, combine the lukewarm water, flours, and sourdough starter or yeast in a medium mixing bowl. Mix thoroughly to combine and allow to rest at warm room temp for 14-16 hours, or overnight. It should expand and have bubbles.

Mix the dough:

1. In the bowl of a stand mixer, mix the water and poolish together. Add in the rye and all-purpose flours. Mix on low until the dough clears the sides of the bowl. Note: Start with 150 grams of water and add in additional water or flour, a little at a time, as needed. Allow the dough to rest (autolyse) for 45 minutes.
2. Add the salt, yeast & molasses. Mix until thoroughly incorporated.
3. Cover the bowl, and let the dough rise in a warm place for 45 minutes. Gently punch the dough down to release the air. Form into a round and place back in the bowl. Let the dough rest for an additional 45 minutes.
4. After the dough has risen, gently punch it down to release the air. Divide the dough into 8-9 equal portions (about 70 grams each) and shape each portion into a ball.
5. Press the bottom (seam side) into a plate of rolled oats. Then place the rolls oats-side down on a baking sheet lined with parchment. Cover the baking sheet with a kitchen towel and let the rolls rise for another 40-50 minutes, or until doubled in size.
6. Preheat your oven to 375°F (190°C). For crustier rolls, preheat the oven to 400°F and place a baking stone or steel on the middle rack.
7. Just before baking, use a sharp knife to cut an X-shape (about ¼ – ½ inch deep) on the top of each roll. Sprinkle coarse Kosher salt over the tops or in the scores. This will add flavor and a decorative touch. You can also sprinkle caraway seeds or sunflower seeds, if desired.
8. Bake the rolls in the preheated oven for about 20-25 minutes, or until they are golden brown and sound hollow when tapped on the bottom.
9. I baked the rolls on a parchment-lined baking sheet on top of a baking steel on the middle shelf of the oven for 10 minutes, then moved the baking sheet up one shelf and baked for 5 minutes; then moved the baking sheet up another shelf and baked for an additional 3-5 minutes. This gave the rolls a more even browning.
10. Once the rolls are baked, move them to a cooling rack, and brush them with melted butter, if desired. Allow them to cool slightly before enjoying.