Preheat the oven to 325˚F.
Set a large heavy saucepan or Dutch oven over medium heat and heat the butter until it melts. When the foaming subsides, add the rest of the ingredients and cook over low heat until warmed through, then put the lid on and pop it into the oven for 1 1/2-2 hours.
Taste and add a little more honey and/or vinegar as you like to suit your taste, add a splash of water or apple juice if it seems dry, and bake a little longer or simmer on the stove top with the lid off if you want to cook it down a bit.
Serve immediately, or refrigerate for a day or two to allow the flavours to develop.