Garlic Balsamic Onion Jam (Slow Caramelized, Sweet and Sticky)

This garlic balsamic onion jam starts with 3 pounds of yellow onions cooked down slowly in butter and olive oil, then finished with sliced garlic, brown sugar and balsamic vinegar until the whole pot turns thick and sticky. It is for anyone who likes a sweet and savory spread to keep in the fridge for burgers, crackers and cheese boards.

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The batch takes about an hour from start to finish and makes about 2 half pints. Most of that hour is the onions cooking down over medium heat, and you will want to stay close to the stove and stir them often so they brown evenly.

What goes into the jam

• 3 lb yellow onions, thinly sliced
• 2 tbsp butter
• 2 tbsp olive oil
• 8 cloves garlic, sliced
• 1/2 cup brown sugar
• 1/2 cup balsamic vinegar
• 1 tsp salt
• 1/2 tsp black pepper

That is the whole list. With so few ingredients, the onions carry the flavor, and the slow cooking is what turns them from sharp and crunchy into something soft and almost syrupy.

Give the onions the full 35 minutes

The most common letdown with onion jam is a pale, stringy batch that tastes mostly of vinegar and sugar. That happens when the onions get rushed. Pale onions still hold a lot of water and a raw bite, so the sugar and balsamic end up sitting on top of them instead of blending in.

The recipe calls for 35 minutes over medium heat, stirring often, until the onions are deep golden. That deep color is where the flavor comes from. In the first stretch the onions will soften and release liquid, and the pile will shrink a lot. After that they start to brown on the bottom of the pan. Stir often enough to scrape up that browning and keep it moving, so it colors the onions instead of scorching.

Slice the onions thin and as even as you can. Even slices soften and brown at the same pace, so you do not end up with some pieces burnt and others still firm. Use a pan that holds all 3 pounds without crowding them into a tall heap, since a deep pile steams more than it browns.

Why the garlic waits until the end

Sliced garlic cooks much faster than onions. If it went in at the start, it would sit in the pan for over half an hour and turn bitter long before the onions were ready. Adding all 8 cloves after the onions are golden gives the garlic just 3 minutes to soften and turn fragrant, which keeps its flavor sweet and mellow inside the jam.

How to make garlic balsamic onion jam

• Melt the 2 tbsp butter with the 2 tbsp olive oil in a large pan over medium heat. Add the 3 lb sliced onions and cook for 35 minutes, stirring often, until they are deep golden.
• Add the 8 sliced garlic cloves and cook for 3 minutes.
• Stir in the 1/2 cup brown sugar, 1/2 cup balsamic vinegar, 1 tsp salt and 1/2 tsp black pepper. Simmer for 15 minutes, until the jam is thick and sticky.
• Spoon the jam into clean jars. Refrigerate for up to 2 weeks, or freeze for up to 3 months. This jam is not meant for water bath canning.

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For a holiday twist on this idea, our caramelized onion cranberry jam adds dried cranberries and thyme and goes beautifully on warm brie.

How to tell when the simmer is done

Once the sugar and vinegar go in, the pan will look loose and wet. Over the 15 minute simmer the liquid cooks down and turns glossy. You are looking for jam that clings to the onions and leaves a slow trail when you drag a spoon across the bottom of the pan. If it still looks watery, the liquid has not reduced enough yet. Keep in mind that it thickens a little more as it cools, so stop when it is sticky rather than waiting for it to set like a paste in the pan.

Where to spread it and how long it keeps

A spoonful on a hot burger is the classic use, where the sweet balsamic cuts through the richness of the meat. It also belongs on a cheese board next to crackers, or spread straight onto a cracker with a slice of cheese for a quick snack.

Keep the jars in the refrigerator for up to 2 weeks. For longer storage, freeze the jam for up to 3 months. Since the recipe makes about 2 half pints, you can keep one jar in the fridge for the week and freeze the other for later.

If you like having a jar of onion jam around, try the smoky bacon balsamic onion jam or the peppery black pepper bacon onion jam . For a fruit spread on the same cheese board, our spiced tomato jam and blackberry jalapeño jam are good company.

A few questions about this jam

Can I can this onion jam in a water bath?

No. The recipe says it is not for water bath canning. Store it in the refrigerator for up to 2 weeks or in the freezer for up to 3 months.

Why are my onions burning before they turn golden?

They are sitting too long without being moved, or the heat has crept above medium. The recipe calls for medium heat and frequent stirring. Scrape the browned bits off the bottom each time you stir so they color the onions instead of burning.

What kind of onions should I use?

The recipe uses yellow onions, 3 pounds in total, thinly sliced. They cook down to the deep golden color the jam needs.

How much jam does one batch make?

About 2 half pints. Three pounds of onions sounds like a lot, but they lose most of their volume during the long cook.

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Written and edited by The Foodie Yummy Kitchen Team

The Foodie Yummy Kitchen Team writes and edits the recipes on Foodie Yummy: classic American potluck salads, holiday sides and easy comfort food, with a few low-carb options. Every recipe lists exact quantities, numbered steps and a printable recipe card, plus notes on swaps, storage and make-ahead timing. Spot a problem with a recipe? Tell us through the contact page and we will correct it. About us