Mix together all ingredients except butter in a deep, heavy-bottomed kettle. Bring to a boil and immediately turn down heat so mixture will bubble gently. Cook uncovered over medium to low heat, stirring regularly to prevent sticking, for 3 hours or until mixture is thick and liquid is absorbed. (Watch and lower heat if mixture is spattering.) After about an hour and a half, begin to taste often. If liquid seems to be evaporating too quickly, add additional vinegar or brandy, depending on taste. If mixture seems too tart, add more sugar. Once mincemeat is cooked down to desired thickness, mix in butter a little bit at a time until well combined. Can or freeze, or store in the refrigerator for up to a month.