I always wanted to try combining two completely different doughs into one loaf. In this case, the body of the boule (French term used to name rounded loaves; literally means ball) was a simple lean dough with a poolish starter which we use mostly for baguettes and epis. It has good flavor, but it is limited by the pre-ferment (the poolish) which isn't as deep as a sour starter. This is why I thought to wrap it in a rye dough. This particular rye has a rye sour starter which is fed twice a day to speed up its metabolism. It contains only wild yeast, no instant yeast; the dough itself is mostly rye flour. Which is a challenge since rye dough does not have the capacity for gluten formation as regular wheat flours do. This, I thought could be problematic during the proofing and baking process, since the rate of expansion of each dough could potentially be very different, in which the lean dough has more capacity for that expansion than the rye dough does. If you compare the crumb of a baguette and a loaf of a 50% rye loaf, they are very different, where the baguette is very open, that of the rye is much tighter. In other words, the rye dough does not expand as much as the lean dough does during the proofing and especially the baking process.
When the boule of lean dough was formed, we had the rye dough ready as well, but it was rolled out very thin, to almost 4 mm. The rye dough was brushed with water, and the boule was placed at its center, with the seam facing up. Then the rye was wrapped around the lean dough, as if wrapping a steamed dumpling.
The dough was proofed in a basket. Once proofed it was turned over onto a floured oven loader. The score was important here; it is always important, but in this case I thought that in order to prevent the rye dough from ripping during the expansion in the oven, I had to cut all the way through the layer of rye, and then some into the lean dough.
It worked well and the result was a very pleasant loaf with a very interesting crust, full of complex flavors and a crisp texture, and a soft, chewy crumb.