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# How to Caramelise Onions (No Sugar)
- URL: https://eatlikeanadult.com/how-to-caramelise-onions-no-sugar/
- Published: 2021-07-27T17:13:25.000Z
- Updated: 2026-09-30T08:19:38.000Z
- Description: Sweet, sticky caramelised onions with no added sugar: just onions, olive oil, salt, time and a splash of balsamic at the end. Make a batch once a week and use it on steaks, burgers, toast and soups. They also freeze well.
- Author: Russell Clamp
- Tags: Healthy How-Tos, #Migrated-1784917438035, #wp, #wp-post, #Import 2026-07-24 18:24

Once a week, I put a big pan of onions on the hob and leave them to it. An hour later, I have a tub of the best thing in my fridge: sweet, sticky caramelised onions with a depth of flavour you can't fake. No sugar, just onions, oil, salt and time.

They go on everything. Steaks, sausages, burgers, stirred through soups and stews. My favourite is sourdough toast with goat's cheese and rocket, piled high with onions. Just thinking about it makes me want to get in the kitchen. A batch is also the start of a very good French onion soup.

Most recipes add sugar to speed things up. It isn't needed. Onions are full of their own sugars, and cooking them slowly brings those out. Once you've made them this way, you won't go back.

### Worth knowing before you start

- **Onions:** Brown or yellow onions give the best result, sweet and rich without needing any help. Red onions work, but they're less jammy.
- **Heat:** Low and slow is the whole trick. Too high and they burn before they sweeten; too low and they steam and never colour.
- **Leave them alone:** Letting the onions sit for 1–3 minutes between stirs gives them time to catch and brown. Stirring constantly slows everything down.
- **Pan:** Use your widest pan so the onions aren't piled up. The salt draws out moisture early on, and a wide pan lets it cook off.
- **The stages:** They go from wet and soft, to juicy, to browning, to properly caramelised. You'll smell the change before you see it.

**Makes** about 1¼ cups (300ml) | Prep 10 mins | Cook 50 mins | Total 1 hour

### Ingredients

- 5 large brown or yellow onions (about 1.1kg / 2½lb)
- 60ml (¼ cup) olive oil
- 1 tsp fine sea salt
- Water, for deglazing
- 1 tbsp balsamic vinegar

### Method

**Step 1: Prepare the onions**

1. Cut the tops and root ends off the onions and peel away the dry, papery outer layers.
2. Halve each onion from top to root.
3. Lay the halves flat and slice into thin half-moons, about 5mm thick.

**Step 2: Soften the onions**

1. Heat the olive oil in a large sauté pan, 28–30cm (11–12in), over a medium-high heat.
2. Test the heat with one slice of onion; it should sizzle straight away.
3. Add the remaining onions and the salt.
4. Toss with tongs for 8–10 minutes, until soft, juicy and noticeably reduced.

**Step 3: Caramelise**

1. Leave the onions for 1–3 minutes without stirring, then stir and scrape up any browned bits from the base of the pan.
2. Keep repeating this for 20–25 minutes. If the base catches or darkens too quickly, add a splash of water and scrape the pan clean.
3. Turn the heat down to medium-low and keep going, stirring every few minutes, for a further 10–15 minutes, until the onions are deep golden brown, soft and jammy. Don't rush this bit.

**Step 4: Finish**

1. Take the pan off the heat and stir in the balsamic vinegar.
2. Leave to cool completely before storing.

### Can you freeze caramelised onions?

Yes, and it's worth doing. Once cool, spoon them into an ice cube tray and freeze until solid. Then tip the cubes into a freezer bag. You can also spread them flat in a bag, about 1cm thick, and snap off what you need. They keep for up to 3 months. Drop them straight into soups and stews from frozen, or thaw overnight in the fridge.

**Storage:** Keep in an airtight container in the fridge for up to 5 days.

**Reheating:** Warm through in a pan with a splash of water.

### Why it's worth the hour

This recipe teaches patience more than technique. There's nothing clever going on: heat, time and knowing when to leave the pan alone. The reward is out of all proportion to the effort. One batch on a Sunday makes a whole week of meals better.

Russell