Roasted Onion Soup

A bowl of onion soup is supremely comforting, the veritable hug in a bowl, rich sticky onions, topped with melted cheese on toast.   This soup contains two types of onions cooked in two different ways, to add texture and richness without the need for beef stock!    

Onion Soup A Perfect Winter Warmer

I love onion soup. There’s nothing better on a cold winter’s evening, and certainly nothing better when you’re feeling stuffy with a cold. The soup is double onion, as it contains white and red onions, both cooked in two different ways by slowly frying and roasting.

It’s a lovely variation on the classic French onion soup, full of flavour and texture!  

Roast Onion Soup

Roasted onions blended into a puree are a simple fuss-free way to add delicious thickness and sweetness to traditional onion soup, so there is no need to mess around thickening it.   

Just with some stock, a glug of wine and you are ready to go. 

You can’t hurry this recipe – properly caramelising onions takes time, so making this is a great way to relax and step back from a busy day.

Why you love this roast onion soup 

• It is delicious and supremely comforting! 
• Once you have done the initial peeling and slicing, aside from giving the onions a stir it is pretty much effortless.
• It is super frugal – you can buy onions very cheaply. 
• It is perfect for batch cooking as the soup can be made ahead and frozen.  

Caramelising onions  

A pan of caramelised onions is a wonderous thing, but it takes time and is something that you cannot rush. Properly caramelising onions will take at least 20 minutes for a coupe of onions, and up to 90 minutes for a big batch.  

There aren’t any real short cuts, although you can cheat and speed it them up a little, but time, a good heavy pan and a heat diffuser are your friends.   Read my hints and tips for perfect caramelised onions. 

How to Make Roast Onion Soup

Step 1 – Place the four whole onions on a baking tray in the oven at GM5/190°C/375°F. Roast for about 45 minutes until they are soft and oozing juice. Halfway through throw in a few cloves of garlic. 

Step 2 – Meanwhile put the sliced onions in a heavy frying pan or casserole dish / Dutch oven with a little olive oil, and a knob of butter.  Sauté them over a low heat until they are soft and starting to caramelize. Keep an eye on them as they cook and nudge them from time to time to stop them sticking and burning. 

Fuss Free Tip 

Use a heavy pan and invest in a heat diffuser (or simmer ring) if you need to.   They cost just a few pounds or dollars, and will provide the consistent low even heat you need for slow cooking on the stove top. 

Season with salt and pepper and some woody herbs half way though. 

Step 3 – When the roast onions and garlic are done, cut the tops off and squeeze the soft insides into a bowl. Then blitz them with a stick blender to make a puree.

Step 4 – If needed transfer your caramelised onions to a saucepan, add the roast onion and garlic puree, pour over the stock and bring to a simmer.   Taste and adjust the seasoning if needed.    To add some colour add a dash of soy sauce or tamari, or even a drop of gravy browning. 

Step 5 – Traditionally French onion soup is served with a slice of toast/crouton covered in melted cheese (usually Gruyère or Emmental). Serve your double onion soup with a slice of your favourite cheese on toast, on the side or on top. If you don’t want the dairy or the extra calories, a simple slice of toast or a chunk of herb bread is delicious too. 

If you enjoyed this recipe, why not try my butternut squash soup with tahini and lemon? Or try these caramelized onions as an accompaniment to cheese, egg or meat dishes.