Ingredients for 2 cups
½ cup balsamic vinegar
1 cup mayonnaise
2 medium onions, thinly sliced, about 4 cups
2 tablespoons vegetable oil
Heat oil in large nonstick skillet over medium-low heat and cook onions, stirring occasionally, until golden brown, about 25 minutes. Stir in vinegar and cook an additional 10 minutes.
Remove from heat and stir in mayonnaise. Season, if desired, with salt and pepper to taste. Serve over steak or spread on turkey or roast beef sandwiches.