Wednesday, 25 January 2012

Slow-Cooker Caramelised Onions

I saw a comment on a forum last week where a poster said she’d caramelised onions in a slow-cooker. To be honest I was very sceptical; surely you need the direct heat of a hob to get a good result? Won’t they just steam and go soggy? How does all the liquid evaporate? There was only one thing to do – have a go!

I had a look on the web, but although there were plenty of people who said they’d done it, no-one seemed to give definitive instructions. They generally seemed to go along the lines of “Add some butter to your onions and cook until done” Yup…really helpful, thanks for that!

So, as usual, I made it up as I went along and, having done it, I can definitely say…it works!

The hardest part was peeling and slicing all the onions, my eyes were streaming like mad, but it's a great way to get a decent quantity of onions caramelised, which you can then portion up and keep in the freezer until you need them. I use them regularly in nut roast, on pizza, in toasted cheese sandwiches, quiches, French onion soup and a zillion other ways so having them ready-to-use is a real time-saver.

2½ kg onions (you may not need them all)
50g butter
1 tbsp dark muscovado sugar
a few grinds of black pepper

Peel and slice enough onions to fill your slow-cooker right to the top. Sprinkle the sugar over the onions then cover with the butter cut into thin slices and a few grinds of black pepper.

Cook for two hours on ‘high’, stir the onions well, then cook for nine hours on ‘low’ (I left it overnight – the smell when we woke was lovely!) In the morning there was much less liquid than I expected, only about ½ cm, so I gave it all a stir and propped open the lid a little to let the steam escape then turned it up to ‘high’ for another two hours. That’s it!

It made six 200g pots which are now tucked away in the freezer, ready for use. I think I can feel a cheese and onion quiche coming on at the weekend….   


  1. That's pretty cool, like you I would have thought 'soggy mush' I'll happily sample if you need a taster ;-)

  2. Did you cook with the lid on, as normal?
    Thanks, I've seen the same conversations but also hoped for more detail, so this is very helpful!

    1. Hi Kavey - I cooked them with the lid on, as normal, but just propped the lid open for the last couple of hours and turned them up to High. I was astonished it worked, TBH, but it did!