The secret to Adam Liaw’s perfect French onion soup? You’ll just have to wait and see

Masterclass

Caramelising onions 101

If you see a recipe for French onion soup that tells you to caramelise onions in 20 minutes, close the tab and move on. You can get some nice fried onions in that time, but if you want to caramelise onions properly, you’ll need at least 45 minutes and maybe even an hour, depending on how far you take them.

While the process is time-consuming, it’s not particularly labour-intensive. Induction cooktops are ideal for this because they give an even, controllable heat across the base of the pot. On my induction cooktop, the setting I use for caramelised onions is the arbitrary number ‘5’ but once you work out the right number or burner setting in your kitchen, it’s the kind of thing you can set and forget.

I use a virtual assistant (“Hey Google”) to set a timer for 6 minutes, then walk away and go on with my day. When the timer goes, I come back and stir the pot with a wooden spoon, scraping up any fond (the brown residue that forms on the base). Then I reset the timer and go back to whatever I was doing. Repeat that 10 times and you have caramelised onions.

Should I make my own beef stock?

I make stock sometimes, and you should too. But I’m also a realist who understands that making stock from scratch every time isn’t entirely compatible with Australian life in the 21st century. If I had to guess, I’d say I make chicken stock about once every two weeks, dashi and other stocks about once a month and beef stock about once a year.

Making beef stock can be a bit of a process – buying bones, roasting them with vegetables, cooking them for a long time and putting up with the smell of boiling bones in the house for a couple of days. But it’s worth doing once in a while, and this soup is the kind of thing I would make with it. (The other thing I make with home-made beef stock is a demi-glace, which you can freeze and use year-round as an excellent sauce base for a good piece of steak.)

Luckily, home-made or shop-bought stock aren’t the only options. For dishes such as soup or risotto, where good-quality stock is important, you can use shop-bought stock as a starting point, then build on it. Great ways to improve a dull liquid commercial stock include simmering it with roasted vegetables (or in this case, onions roasted in halves with the skin on); adding extra herbs; or boosting the savouriness with a little soy sauce, fish sauce or even a bit of powdered stock.

When I’m making soups or sauces with commercial stocks, I like to add gelatine, which is often removed in the manufacturing process to prevent the stock from solidifying on the shelf or in the fridge. Gelatine is important for a dish like this – it gives the soup lip-smacking richness. Thankfully, you can buy packet stock anywhere you buy powdered gelatine.

No flour

Adding a few tablespoons of flour to the caramelised onions can give the soup more body, but I recommend against it. One of the things to appreciate about French onion soup is that it’s a light, almost consommé-like soup enriched by the onions, with toasted baguette providing extra texture. Thickening the soup with flour makes it heavier, and can make the end product taste like drinking a bowl of gravy.

Under the grill

The French name for this soup is “soupe à l’oignon gratinée” or onion soup gratin, so the gratineed cheese is an integral part of the finished product. It’s traditionally served in a pot-bellied, double-handled French cooking vessel called a marmite (pronounced marr-meet), which gave its name to the British sandwich spread Marmite (and in turn influenced the name of our own Vegemite).

Most crockery can happily go into the oven, even if it’s not specifically labelled “ovenproof”. Porcelain is fired at much higher temperatures than a domestic oven will reach, and if your bowls are filled with soup, they aren’t likely to crack as the heat density of the soup will stop the bowl from overheating. Grilling can be more aggressive, however, so if you don’t want to risk your regular bowls, either get some oven-safe marmites, use ramekins or cocottes (individual baking dishes), or simply grill the cheesy baguette slices separately and drop them onto the soup to serve.

The main problem with grilling at home is that most modern ovens only grill with the door closed, and even then, only to a particular temperature, so the heating element turns off once that temperature is reached. For that reason, I often grill when the oven is starting to warm up. The top element will stay on longer, ensuring a nice gratinated surface.