Cook duck kebab. To do this, turn the duck fillet with browned onions through a meat grinder. Form a kebab, fry in vegetable oil, bring in the oven until tender, 5-7 minutes at a temperature of 180 C.
Fry thinly sliced onion in vegetable oil until soft, add butter and sugar. Caramelize over medium-high heat, add red wine, reduce to a boil, add chicken broth and beef broth or demi-glace sauce. Boil until the consistency of a thick soup.
Serve onion soup with duck kebab topped with onion fries.