In a large bowl add warm water and starter. Mix until combined.
Add flour and salt.
Combine everything until a shaggy dough forms.
Let sit for 35 minutes.
Do a set of stretch and folds. Cover and let sit for 30 minutes.
Switch to coil folds. Cover and let sit for 30 minutes.
Zest lemons and mix with sugar. Sprinkle over the dough during coil folds.
Continue bulk fermenting until ready.
Prepare cream cheese filling by mixing cream cheese, confectioners sugar, and vanilla.
Shape the dough into a rectangle, spread cream cheese mixture, add blueberries, fold and shape into a ball.
Cold proof in the fridge for 12-48 hours.
Preheat oven to 500°F. Bake the loaf in a Dutch oven at 450°F for 40 minutes with the lid on and 12 minutes with the lid off.
Let the bread cool for at least 2 hours before serving.