Melt the butter in a heavy-based 3- or 4-qt. saucepan over medium heat. Add the onions and cook, stirring occasionally, until they're very soft and stringy looking but not brown, 12 to 15 min. (Reduce the heat to medium low if they start to brown.) Add the wine and honey, reduce the heat to medium low if you haven't already, and simmer, stirring occasionally, until the mixture is thick and jammy, another 20 to 30 min. Remove from heat and stir in the vinegar; season with salt and pepper to taste.
nutrition information (per serving):
per 1 Tbs.;
Photo: Scott Phillips