The great art of the gratin

We were having dad’s fish au gratin, which didn’t sound French at all in my dad’s broad Yorkshire accent. More like a glottal fish-o-gra-’an. Oh but I loved it. Fish topped with onions and braised in a pan until they were sweetly caramelised, then spooned onto fillets of almost-done pan-fried white fish and smothered in his cheese sauce, and popped under the grill to turn it a golden, gooey, molten brown.

You had to live a little and grow up before you realised that there were many other dishes like that; that the technique was applied to potato bakes such as Pommes Dauphinois, lasagne from Italy, Greek zucchini bakes, and everyone’s favourite childhood supper, macaroni cheese. And what is a perfect mound of cauliflower cheese, finished under the grill, if not a gratin… and better still if it has a few light breadcrumbs on top to turn perfecton even better.

But halved plump, ripe tomatoes can be topped with Parmigiano-Reggiano, breadcrumbs, herbs and capers for a delicious taste of Sicily. Brinjal/aubergine/eggplant topped with a garlicky melange of Parmesan, feta, and a great melting cheese such as Gruyère or, why not, Cheddar, and you’re in Mediterranean heaven within one mouthful.

But, for me, French onion soup is the ultimate gratin as well as the ultimate peasant dish, a term not intended to denigrate the poor people for whom it was once a staple meal but to identify the dish as a part of that cuisine. Peasant cuisine, one of food’s common denominators.

The soup is all about creating a beautiful dish out of next to nothing; about producing mountains of flavour from the most modest of ingredients: the humble onion. It’s also all about the caramelising of the onions. The extraction, through time, gentle heat and patience, of every iota of flavour the onion could possibly give you.

Its other core flavours are beef stock and cheese, though the latter is only the finishing touch, a mound of it on top of croutons (slices of toasted baguette) which is then finished in the oven or under the grill for the cheese to melt into the bread and form a cheesy, insanely desirable crust, below which is the invisible lake of intensely flavoured soup, packed with onions.

In Paris it is called Soupe l’oignon a là Parisienne or Soupe l’oignon gratinée; so we could call it gratinated French onion soup.

Though there have been onion soups in many cuisines since antiquity, and yes, the Romans had an onion soup too, it is the French onion soup that is best known, and has been particularly popular in the last 60 or so years after its heyday as a Parisian street food for the masses in its modern 18-century origins. 

A spoonful of sugar? Some recipes call for it, others don’t. The caramelisation of onions releases their own sugars which is why they caramelise given plenty of time and patience. But with the great quantity of onion I used (they were massive ones), I felt that a little sugar (caramel sugar in my case though most recipes would call for brown) was hardly going to inhibit the caramelisation process.

The cheese in its Parisian era would have been Comté, from the Franche-Comté province bordering Switzerland, though today it’s more common to use Gruyère or another Swiss cheese such as Fontina. You’ll see that in my recipe here I use Mozzarella, which is also sometimes used in modern versions. Get Gruyère or Fontina if you can. Parmesan is frequently used these days in addition to the main choice of cheese. It’s honestly not essential that you include it; stick to just one if you prefer, Parmesan being such an unflinchingly commanding cheese. I did use it since I was using Mozzarella; if it had been Gruyère I may have left the Parmesan out.

I have in the past often roasted whole or halved onions with thyme, for three hours or more to extract maximum flavour from them even before chopping up the roasted onions and then caramelising them further in a pan on the stove. You can of course do this, but to caramelise thinly sliced onions from scratch in a deep, heavy frying pan as I did this time will give them all the flavour they need providing that you do give them as much time as you can; two hours at a minimum, or even more as long as you are careful not to take them too far inadvertently and risk giving them a burnt or “caught” flavour.

It was a chilly Sunday night when I made the soup, the kind of night when a broth becomes a most desirable and moreish thing. Especially a French onion soup with that marvellous cheesy, crunchy topping to break through. Here is the recipe. DM/TGIFood

Tony Jackman is Galliova Food Champion 2021. His book, foodSTUFF, is available in the DM Shop. Buy it here. 

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