Caramelised Onion Jam with Balsamic Vinegar

Sticky, sweet and deeply savoury – the ultimate cheese-board companion.

If you love deeply savoury flavours with a hint of sweetness, this Caramelised Onion Jam with Balsamic Vinegar is about to become a fridge staple. Slow-cooked onions are transformed into a rich, glossy jam that’s perfect for cheese boards, burgers and sandwiches.

Caramelised onion jam in a glass jar with thyme, served on toasted bread on a white timber table, styled with balsamic vinegar and olive oil in soft natural light.

This is an easy, no-fuss recipe made with simple ingredients, but the flavour is anything but basic. The balsamic vinegar adds depth and balance, cutting through the sweetness for a truly addictive condiment you’ll want to put on everything. Slowly cooked onions break down into a rich, glossy jam, with balsamic vinegar adding just enough acidity to balance the sweetness. It’s the kind of condiment that instantly elevates simple meals, whether you’re building a cheese board, dressing up a burger or adding a savoury hit to sandwiches and wraps.

Why You’ll Love This Sticky Onion Jam

Simple pantry ingredients – nothing fancy or hard to find
Big flavour, low effort – slow cooking does all the work
Incredibly versatile – perfect for cheese, burgers, roasts and tarts
Make-ahead friendly -keeps well in the fridge for easy entertaining
Naturally rich and glossy – no thickeners or preservatives

Top-down view of caramelised onion jam ingredients on a white timber surface, including whole brown onions, fresh thyme, brown sugar, balsamic vinegar, oil, butter, salt and pepper in small bowls under soft natural light.

Ingredients In Caramelised Onion Jam

Olive oil & butter – Using both gives you flavour and control. The oil stops the butter burning, while the butter adds richness.
Brown onions – The star of the show. Brown onions caramelise beautifully, breaking down into a naturally sweet, jammy base.
Salt – Draws moisture out of the onions early on, helping them soften and caramelise properly.
Brown sugar – Enhances the natural sweetness of the onions and helps create that glossy, sticky finish.
Balsamic vinegar – Adds acidity to balance the sweetness and gives the jam depth and richness.
Fresh thyme (optional) – Adds an earthy, aromatic note without overpowering the onions
Black pepper – A subtle savoury kick that rounds everything out.

Variations To Try

Once you’ve mastered the base recipe, onion jam is incredibly easy to customise. Add crispy bacon at the start for a smoky bacon and onion jam, or stir through a splash of red wine or port for extra richness. A pinch of chilli flakes or a spoonful of chilli jam will give it a gentle heat, while a teaspoon of wholegrain mustard adds a savoury edge that works beautifully with cheese. You can even swap thyme for rosemary or bay leaves depending on what you have on hand.

Sliced onions cooking in a non-stick frying pan, turning soft and translucent on a stovetop in natural light.

Caramelising onions in a frying pan with balsamic vinegar and brown sugar added, shown mid-cook in natural light.

Top Tips for Making the Caramelised Onion Jam

Slice the onions evenly so they cook at the same rate.
Use a wide, heavy-based pan to encourage evaporation and caramelisation.
Keep the heat low and be patient — rushing will burn the onions instead of caramelising them.
Stir regularly, especially towards the end, to prevent sticking.
If the pan gets too dry, add a tablespoon of water and scrape up the sticky bits — that’s flavour.

How To Serve

Caramelised onion jam is one of those condiments that works with almost everything. Spoon it onto cheese boards with brie, cheddar or blue cheese, layer it into burgers and steak sandwiches, or swirl it through savoury tarts and quiches. It’s also fantastic alongside roast meats, sausages or grilled vegetables, and makes an easy upgrade to wraps, toasties and even scrambled eggs.

Spoon lifting glossy caramelised onion jam with balsamic from a glass jar on a white timber surface, styled with thyme and bread in soft natural light.

Toast topped with caramelised onion jam and a wedge of brie cheese on a white timber table, styled with thyme and a spoon of onion jam in soft natural light.

Storage

Allow the onion jam to cool completely before transferring it to a clean, airtight container. Store in the fridge for up to 2 weeks. Always use a clean spoon when serving to keep it fresh for longer.

FAQ’s

Can I freeze onion jam?

Yes. Onion jam freezes well for up to 3 months. Thaw in the fridge overnight before using.

Can I use red onions instead of brown?

You can, but the flavour will be slightly sharper and less rich. Brown onions give the best caramelised result.

Why is my onion jam bitter?

This usually happens if the onions cook too fast or burn. Keep the heat low and cook slowly for best results.

Do I need to sterilise jars?

Not for fridge storage. Sterilising is only necessary if you plan to preserve it long-term.

If you make this caramelised onion jam, I’d love to hear how you use it — leave a comment below and let me know, or rate the recipe if you enjoyed it. And don’t forget to check out my Absolute Best Chilli Jam for another flavour-packed favourite.

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