First, make the peach syrup. Add 2 sliced and peeled peaches (about 310 grams) to a pan with 1 ⅓ cup water and ¼ cup sugar. Bring mix to a boil and then simmer for 10 minutes. Let the liquid cool for a few minutes before straining the liquid and adding it into a jar. Cover the peaches that were strained out and place them in the fridge for later. Let it cool to room temperature before adding it to the sourdough bread. In total, you will want 325 grams of liquid to add to the loaf. If some of the moisture is cooked out of the peach juice simply add more water to the loaf to reach 325 grams.2 fresh peaches- peeled and diced, 325 grams water, 50 grams sugar
Mix together flour, cooled peach juice, sourdough starter, and salt until a shaggy dough is formed. Cover the dough and let sit at room temperature.500 grams bread flour, 325 grams peach juice, 50 grams active and bubbly sourdough starter, 10 grams salt
About 30 minutes later, perform a set of stretch and fold and then leave the dough to sit covered. If you have time do this one or two more times with about 30 minutes in between.
Let the dough sit covered for 8-12 hours, until the dough is risen about 75%.
Make the streusel by mixing the butter, sugar, flour, oats, cinnamon, and optional pecans. Squeeze the butter to break it up in the mixture until crumbly.57 grams butter, 55 grams brown sugar, 46 grams flour, 30 grams oats, 1 gram cinnamon, 27 grams pecans chopped, optional
Take 140 grams (½ cup) of the reserved softened peaches from the peach juice and chop into small pieces. Do not use all of the peaches as your dough will be way too wet.
Spread the dough out into a large rectangle on an unfloured surface. Sprinkle ⅔ of the struesel and peaches on the dough. Roll the dough up like a cinnamon roll and then sprinkle a little bit more streusel (leaving a little more for the top) and the remaining chopped peaches.
Roll up the dough and gently shape either into an oval or round shape.
Add the remaining streusel to the banneton basket liner and then add the dough.
Place the dough in the fridge for the second proof. Ideally you want to wait at least 8 hours but you can do it earlier depending on when you want to bake.
When ready to bake, preheat the oven and dutch oven to 450℉.
Score the dough and place it into the dutch oven. Bake covered, with the lid on, for 45 minutes. If you want to brown the top more, you can bake for an additional 3-5 minutes with the lid off just watch because the crumble can burn on top.
Remove the bread from the dutch oven and place on a cooling rack to cool.
Notes
If you want a sweeter loaf you can add in an additional 50 grams of sugar when mixing the ingredients for the dough. If you prefer to bake the same day, leave the dough on the counter for the second rise. Within 2-4 hours your dough should be ready to bake. To know when it is ready you will poke the dough with a floured finger. If it springs back immediately it needs more time. If it doesn't spring at all it is overproofed and needs baked asap. If it slowly fills back in it is ready to use.