Lightly roast the hazelnuts in a pan without fat and allow to cool.
In the meantime, grate the zucchini coarsely, knead well and evenly in the food processor together with the flour, salt and sourdough. Roughly chop the cooled hazelnuts and fold into the dough.
Grease and flour a large loaf pan (suitable for sourdough), then add the dough and let it rise in the oven at 50 ° C until the volume of the dough in the pan has increased significantly (approx. 2-3 h).
Then set the oven to 180 ° C and bake the bread for about 50-55 minutes.