Mix the sourdough with the salt and let stand for a few minutes.
Mix the wine with the hot (not boiling) water and add to the sourdough together with the flour. Knead well and for a long time (food processor: approx. 8-10 minutes; by hand approx. 15-20 minutes). Then let it rest for 25 - 30 minutes (= stick cooking).
In the meantime, finely dice the onion and bacon (amount as desired) and fry or leave them out in a pan without adding any additional fat. Allow to cool slightly.
After stick cooking, knead in the onions and bacon thoroughly (by hand), then work the dough well and shape into a loaf. Cover and let rise in a warm place for approx. 1 1/2 - 2 hours (ideally in a proofing basket or bowl) until the volume has increased significantly (this can, however, take longer or shorter depending on the leavening power of the sourdough).
Preheat the oven to 250 ° C top / bottom heat.
Place the loaf on the baking sheet, cut carefully with a sharp knife (or a razor blade) and immediately put it in the fully heated oven; Do this vigorously (spray water into the oven with a flower sprayer). After 10 minutes, let off the steam, turn the heat down to 180 ° C and finish baking in 40 - 45 minutes.
The stated amounts result in a bread of approx. 600 g.
Note on sourdough: this is real, live sourdough; not about ready-made sourdough from the hose or dry sourdough powder. You can easily make sourdough yourself; Instructions are available here in the Bread & Rolls forum of the CK.