Combine the honey, duck stock, and chopped thyme in a small saucepan. Heat to boiling, then reduce the heat and simmer 5 minutes. Season with the vinegar if using and salt and pepper to taste.
Cut the ducks into quarters and arrange 2 quarters on each of 4 serving plates (see Note 4). Warm the honey mixture and spoon over the duck. The ideal accompaniment is little potatoes roasted in the rendered duck fat and blanched carrots sautéed in butter and sprinkled with parsley.