Balsamic onion jam is one of those things that generally makes people cock their head to the side and say, "huh?" Generally that's followed by, "is it sweet? What do you put it on?"
Well, dear reader, it is sweet in the sense that it's loaded with caramelized onion goodness and sweet-tart balsamic vinegar, but it isn't breakfast jam style sweet. I use a combination of onions in my jam to provide a balance of flavors and textures to the finished product.
As to what you should put it on, basically anything that is tasty with onions will be even tastier with balsamic onion jam. Shutterbean has a great list of uses including pizza, pasta, steak, and grilled cheese. I will add my morel brioche to that list, as well as baked brie with diced apples and toasted walnuts, or a tomato and gruyere tart. Is your mouth watering as much as mine is? Well then, let's get to it!
Balsamic Onion Jam
2 tablespoons olive oil
4 cups sweet onion (such as Vidalia or Walla Walla Sweets), divided
2 cups yellow onion
1 cup leek
1 teaspoon dried thyme
1 tablespoon brown sugar
1/2 cup balsamic vinegar
fresh black pepper
Julienne all onions, reserving 2 cups of the sweet onions.
Heat a large skillet over low heat. Add olive oil and all onions, except for the 2 cups reserved sweet onions. Sprinkle with salt. Cook slowly over low heat so that onions caramelize. This will take a long time. A looooong time. Just be patient. The end result is so worth it.
Deglaze pan with balsamic vinegar. Add reserved 2 cups of sweet onions, brown sugar, and thyme. Reduce over low heat until vinegar is absorbed/cooked off. Turn off heat and season to taste with salt and pepper. Pack in jam jar and store in fridge for up to two weeks.