Quarter the onions. Heat butter and sauté onions until translucent.
Coarsely chop sage, sprinkle over onions, pour in wine and sauté for 3 minutes.
Cut apples into eighths, remove core. Mix apples with apple syrup and add to onions. Season with salt, pepper and sugar, steam for 5 to 7 minutes and season.
Serve with short-roasted meat.