Caramelised Red Onion & Balsamic Jam

This homemade red onion jam combines the natural sweetness of the onions with rich balsamic vinegar, a little honey and thyme. The result is a beautifully rich, sticky jam with a lovely balance of sweet and savoury flavours.

It tastes amazing with mature cheddar on a slice of rye, soda or sourdough bread, but it's equally delicious in sandwiches, alongside roasted meats or in burgers. I even love dolloping some on top of a curry!

As with most of my recipes, I swap refined sugar for honey. Because we're slowly caramelising the onions and bringing out their natural sweetness, a little honey goes a long way.

The secret is patience. The onions need time to soften and caramelise gently, but there's very little effort involved, and the end result is well worth the wait.

Unlike traditional preserves, this is a small-batch onion jam designed to be kept in the fridge and enjoyed fresh.

Recipe Overview

Prep Time: 10 minutes

Cook Time: 45–55 minutes

Makes: Approximately 1 small jar (250–300g)

Servings: Approximately 12 (20g each)

Ingredients

• 500g red onions (approximately 4 medium), peeled and thinly sliced

• 1 tbsp cold-pressed rapeseed oil

• 3 tbsp balsamic vinegar (45ml)

• 2 tbsp runny honey (approximately 40g), or maple syrup

• 1 tbsp red wine vinegar (15ml)

• ½ tsp dried thyme or 2 small sprigs fresh thyme

• A small pinch of sea salt

• Freshly ground black pepper

• 2–3 tbsp water, if needed

Method

1. Prepare the onions. Peel and thinly slice the red onions into even half-moons, approximately 3mm thick.

2. Soften and caramelise. Heat the rapeseed oil in a heavy-based saucepan over a low to medium heat. Add the onions and a small pinch of salt. Cook uncovered for approximately 25–30 minutes, stirring regularly, until the onions have softened, reduced in volume and started to caramelise. Reduce the heat if they begin to catch.

3. Add the flavourings. Stir in the balsamic vinegar, red wine vinegar, honey, thyme and freshly ground black pepper. Scrape up any caramelised bits from the bottom of the pan.

4. Reduce gently. Continue cooking uncovered over a low heat for another 15–25 minutes, stirring frequently, until the onions become dark, glossy and beautifully sticky. There should be very little free liquid remaining. If the mixture begins to catch, add a tablespoon of water.

5. Taste and adjust. Remove from the heat and allow a small spoonful to cool before tasting. Add a little more vinegar if you prefer a sharper flavour, or a touch more honey if you like it sweeter.

6. Cool and store. Remove any thyme sprigs. Allow the jam to cool briefly, then transfer to a clean glass jar or airtight container. Refrigerate promptly.

Nutrition (per 20g serving, approx.)

• Calories: 35 kcal

• Protein: 0.3g

• Carbohydrates: 6g

• Healthy fats: 1g

• Fibre: 0.6g

Values are approximate and will vary depending on ingredients used and the final yield.

Why This Works — The 60Fit Approach

• Fibre and plant compounds: Red onions provide dietary fibre, including fructans, and naturally occurring plant compounds such as quercetin.

• A little goes a long way: Slow caramelisation develops the onions' natural sweetness and creates a rich flavour, so a small spoonful is all you need.

• A balance of flavours: Balsamic vinegar adds depth and acidity, while a modest amount of honey balances the sharpness without making the jam overly sweet.

• Unsaturated fats: Cold-pressed rapeseed oil provides predominantly unsaturated fats and has a mild flavour that works particularly well with the onions.

60Fit Tip

Patience is the secret to this recipe. Cook the onions slowly and gently rather than trying to speed up the process. They should become soft, sweet and caramelised before you add the vinegar and honey.

The finished jam will thicken a little further as it cools.

For a vegan version, simply replace the honey with maple syrup.

Storage: This is a refrigerated onion jam, not a shelf-stable preserve. Keep in a clean, airtight container in the fridge at 5°C or below and use within 5-7 days, or freeze small portions for longer storage. Sterilising the jar alone does not make this recipe suitable for cupboard storage.