Mix 700 grams of your water, all of the flour, and the cinnamon together, but no levain. Let this mixture sit for about 30 minutes.
After you've let this rest, add your levain and squeeze into the mix. Don't tear at the dough, just gentle incorporation. Once this is fully incorporated, let it rest for 5 minutes.
Add your remaining water, the salt, and the raisins into the mix. Use the same technique to incorporate everything into the mix. Make sure you aren't tearing or pulling at the dough too hard. It will take some time but it will slowly absorb all of the water.
To evenly distribute the raisins, you can fold your dough over a few times until you are satisfied with the level of incorporation.
Since I call this an "easy" recipe, you'll let this mixture ferment in a bowl for up to 6 hours. My temperature at home is usually between 72-75. Make sure you have a general idea of how warm your environment and adjust the bulk fermentation time accordingly. What you're looking for at the end is a bubbly surface and a weblike structure at the bottom of the dough.
Once you are happy with your bulk fermentation, you can dump your dough out onto a floured work surface and divide into two.
We won't be pre-shaping this dough, so simply apply your final shape. If needed, you can slightly degas your dough. For the final shape, you can use a tension roll, a simple round, or stitching. Or anything else. You can check out my Instagram feed for various shaping videos.
Place your shaped dough into a floured bowl, banneton, couch, or kitchen cloth. Any vessel that helps maintain the structure works, but you can also flour a cutting board and place your shaped dough, seam side down, there. Cover with a plastic bag or cloth and let proof for up to 3 hours.
What you're looking for after the proof is a slight jiggle and a bouncy surface when you press down on the dough. Use a wet fingertip to do this. Your dough should have noticeably gained some volume but doesn't have to be overflowing out of your proofing vessel.
Pre-heat your oven with the cast iron or baking stone inside to 500f. If you have a temperature gun, it's best to check the actual baking surface for the temperature. Sometimes your oven will be done preheating but your cast iron may be a bit cooler than desired.
Once you load your loaf, turn the heat down to 475 and bake for 20 minutes covered. If using a pizza stone, you can use a spray bottle to generate steam in your oven. I would also recommend putting your loaf seam side up in this case to get a natural, rustic score.
I like to turn the heat back up to 500 after the initial part of the bake and move my bread up to the top rack to get it as dark as possible. I love to bake bold and have that nice flavorful crust.
Once your bread is done baking, there's only one thing left to do. Enjoy!
