Melt butter in a large kettle. Add onions and sweet mix. Cook over medium low heat until onions are caramelized. Divide onions between 7 quarts jars. Heat broth, salt, garlic, and red wine vinegar together until boiling. Divide between the jars adding additional water if needed to fill jars with a 1 inch head space. Add lids and rings. Pressure can at 10 psi for 30 minutes. 7 quarts.

This can also be frozen in pint/quart freezer containers.