Caramelized Onion Balsamic Jam

Caramelized onion jam with balsamic vinegar brings a rich sweet and tangy layer to almost anything from cheese platters to roasted meats. This is one of my go-to recipes for transforming basic onions into something sophisticated yet deeply comforting. I started making this when I wanted a more flavorful sandwich spread and now I almost always keep a jar in my fridge.

I first made this for a holiday cheese board and it disappeared in no time. Since then it is a must-have for family gatherings and simple lunches alike.

Ingredients

• Sweet onion: These add natural sweetness and depth. Choose firm onions that feel heavy for their size
• Olive oil or avocado oil: Helps the onions caramelize and adds a rich background flavor. Pick oil that smells fresh, not stale
• Cane sugar, brown sugar or coconut sugar: Any of these work and each brings their own note. Try cane sugar for classic balance or coconut sugar for a hint of caramel
• Thyme: Its earthy aroma brings out the savoriness. Fresh sprigs make a difference but dried thyme can work too
• Bay leaf: Adds subtle floral complexity and rounds out the flavors. Choose whole dried leaves with no cracks
• Balsamic vinegar or red wine vinegar: For tangy brightness and jammy flavor. Go for a well-aged vinegar for richer taste
• Salt: Brings everything together and sharpens the finish. Use fine salt and adjust to your preference

Step-by-Step Instructions

Prepare the Onions:

Peel and dice or slice the onions. Try to keep your cuts even so they cook uniformly. A sharp knife makes things quicker.

Sauté the Onions:

Heat the oil in a heavy-bottomed pan over medium-high until shimmering. Toss in the onions. Stir every few minutes and cook for fifteen minutes until the onions turn golden and feel soft. The slow cooking draws out their natural sugars.

Add Herbs and Gently Infuse:

Lower the heat to low. Add in the thyme sprigs and bay leaf. Stir and let them release their flavors for three to five minutes. Your kitchen will smell amazing.

Sweeten and Melt:

Sprinkle the sugar evenly over the onions but do not stir. Let the sugar sit on top for five minutes. The steam gently melts it into the onion base.

Caramelize the Mix:

Raise the heat to high without stirring. Watch closely for five minutes as the sugar transforms into a golden caramel glaze. Be patient but do not step away. This step adds all the magic.

Simmer with Balsamic:

Pour in the balsamic vinegar and give it all a good stir. Drop the heat to low and simmer for about five minutes. The mixture should thicken noticeably. Test by dragging your spoon along the pan and if the bottom stays visible for a few seconds it is ready.

Finish and Store:

Remove the thyme and bay leaf, then taste. Adjust salt if needed. Let it cool to room temperature and spoon into clean jars for storage.

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There is something about sweet onion slow-cooked in balsamic that never fails to remind me of my grandmother's kitchen during the holidays. Her favorite touch was always that bay leaf which makes everything taste a bit more special.

How to Store Your Onion Jam

Once completely cooled, store your onion jam in a clean tightly sealed glass jar. It keeps in the fridge for up to two weeks. For longer storage, freeze small portions in airtight containers using freezer-safe glass or silicone. The flavor actually deepens with a day or two of chilling.

Simple Ingredient Swaps

No sweet onions? Use yellow, white, or red onions for a slightly different flavor profile. Apple cider vinegar can stand in for balsamic if you want a lighter, brighter taste. Fresh rosemary or tarragon works well in place of thyme for a twist.

Serving Ideas to Try

This jam is incredible with cheese boards, especially with sharp cheddar or goat cheese. I love it piled onto a toasted slice of baguette with a swipe of soft cheese. Stir a spoonful into sour cream for an instant dip or dollop onto burgers and grilled sausages. It also livens up roasted veggies and sandwiches.

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This caramelized onion jam is an absolute game-changer for your kitchen staples, adding a burst of flavor with every spoonful.

Frequently Asked Questions

→ How long does caramelized onion jam last?

When properly stored in sterilized jars in the refrigerator, caramelized onion jam can last 2-3 weeks. For longer storage, freeze in small portions for up to 3 months.

→ What can I serve with caramelized onion jam?

Caramelized onion jam pairs beautifully with cheese boards, especially with brie or goat cheese. It's also excellent on burgers, sandwiches, crostini, or stirred into pasta dishes and risottos.

→ Can I substitute the sugar in this onion jam?

Yes, you can substitute cane sugar with brown sugar, coconut sugar, or even honey (use about 2/3 the amount). Each will provide slightly different flavor notes to the final jam.

→ Why shouldn't I stir the sugar when making onion jam?

Stirring sugar immediately can cause it to seize and form clumps. Letting it melt undisturbed over the onions creates a smoother caramelization process and more consistent texture.

→ Can I use red wine vinegar instead of balsamic?

Yes, red wine vinegar works well as a substitute for balsamic vinegar. The flavor profile will be slightly less sweet and rich, but still delicious. You might want to add a touch more sugar to compensate.

→ How do I know when my onion jam is ready?

The jam is ready when it has thickened considerably and drawing a spoon across the bottom of the pan leaves a clear trail for several seconds before filling back in.