Caramelized Red Onion Relish (Canning) - cooking recipe

Ingredients

2 large red onions, peeled and very thinly sliced (use a mandoline or food processor with slicing blade)
1/2 cup firmly packed brown sugar
1 cup dry red wine
3 tablespoons balsamic vinegar
salt and pepper (to taste)

Preparation

Combine onions and sugar in a heavy non-stick skillet. Cook, uncovered, over medium-high heat for about 25 minutes or until onions are golden and starting to caramelize, stirring frequently.
Stir in wine and balsamic vinegar. Bring to a boil on high, then reduce heat to low and cook about 15 minutes, or until most of the liquid has evaporated, stirring frequently.
Season to taste and cool briefly.
Ladle relish into hot half-pint jars, leaving 1/2-inch headspace. Process in a boiling water bath for 10 minutes.