Peel the onions sparingly, i.e. remove as little red skin as possible. Cut onions lengthwise into fans so that they still hang together a little at the root end.
Melt the powdered sugar in a frying pan. Add the butter and gently caramelize both. Pour in the onions and turn them to the other side. Add the rosemary and bay leaf. Gradually add the red wine. Season the onions with salt, add pepper and season with the two vinegars. Cover and stew quietly at low temperature for 15 minutes. Then remove the lid and cook the liquid a little bit.
The confit of red onions can be served warm or cooled as a side dish.
Our tip: Use high quality red wine for a particularly fine taste!