The following two loaves were made using the recipe from Teresa at Northwest Sourdough. I had to do a few conversions from cups to grams but managed to come up with a workable recipe. The only thing I've added is a bit of wholemeal flour for the taste I like.
There have been a few questions here and there about crust blister. With these loaves, they are at 60% hydration and spend 12 hours in the fridge, so they get a bit of a dryish surface on them. When I put them in the oven I spray the top heavily and repeat about 6 minutes later. I also throw 5 ice blocks in a tray in the bottom of the oven at the start.
Bingo, blisters on the crust.