This recipe is just so – ugh, forgive me for using this word in reference to food – sexy for something that is made of so many unsexy foods (onions, bones, a lot of cheese, even more onions). It’s deep and dark and the absolute definition of sumptuousness. There is no world in which this could not so indulgently comforting. The process of making the stock is ritualistically satisfying, and you get to buy a giant sack of bones from your butcher, so that should put some spring in your step. Plus the ever-trendy bone broth gets a chance to shine in something not yet overrun by hipster meddling and nonsense, so everyone wins.
BA’s Best: French Onion Soup w/ Bone Broth
Taken from BA’s Best arsenal, with some minor tweaking
4 lb beef bones
1 tbsp vegetable oil
2 large yellow onions, chopped
6 celery stalks, chopped
1 lb carrots, peeled and chopped
¼ cup tomato paste
1 head of garlic, halved crosswise
4 sprigs of thyme
1 bay leaf
Soup + Assembly:
3 tbsp vegetable oil
1 tbsp unsalted butter
1 head of garlic, halved crosswise
4 lb yellow onions
3 tbsp dry sherry (white wine will work in a pinch, but sherry is ideal)
6 sprigs of thyme
1 bay leaf
6 ½-inch thick slices baguette, toasted
6 slices gruyere cheese
6 slices emmenthal cheese
Make the bone broth first. Preheat the oven to 425 degrees F. Place a wire rack inside a large rimmed baking sheet and set the beef bones on top. Roast the bones for ~45 minutes, until deep golden-brown and sizzling madly. Transfer to a very large pot and cover with 3-5 quarts of water (about the same as litres), depending on the depth of your pot. Bring to a simmer over medium heat, then skim off any foam or grayish bits that rise to the surface. Remove from the heat.
While the bones simmer, heat the vegetable oil in another large pot over medium-high (or you can wait it out and wash then re-use the bone-cooking pot, reserving the bones and water in a large mixing bowl). Add the onions, celery, and carrots (along with a generous 3-finger pinch of kosher salt), then cook, stirring occasionally, until the veggies start to caramelize, ~10-15 minutes. Add the tomato paste and cook, stirring often, until the veggies have darkened slightly, ~5 minutes. Pour the bones and liquid into the pot along with the garlic, thyme, and bay leaves. Bring to a boil, reduce the heat to low, and cook at a very gentle simmer. Top up the water as needed to keep the liquid level constant throughout cooking. Simmer the stock for ~2 hours, until it is deeply flavourful. Taste and season lightly (it needn’t be very salty, but it should not be bland). Strain the stock through a fine-sieve and skim any fat off the top with a large spoon or a smaller sieve (like the kind you use for dusting cinnamon onto cappuccinos – surely you have one of those ones, no?). Set aside until ready to use, or let cool slightly before refrigerating and using within the week.
Now onto the soup. Heat the vegetable oil and butter in a very large pot set over medium heat. Place the garlic halves, cut side down, into the buttery oil and cook undisturbed for ~4 minutes, or until lightly golden brown and fragrant. Transfer garlic to a small plate. Add the onions to the same pot, season generously with kosher salt and freshly ground black pepper, and let them start to cook down. Stir the onions occasionally at first, then, once they have wilted down quite considerably, start stirring more frequently. The onions should be kept cooking over medium (don’t touch the dial, for real), being stirred as needed, until they have reached a deep golden-brown colour. This will take a solid 60-75 minutes as the onions will release a LOT of water prior to browning. The browning process happens quite gradually – at first you will notice them turning a very creamy beige, then they will slowly transition into more of a yellow tone, before moving into the deeper golden shades that make caramelized onions one of the most perfect foods imaginable.
Add in the sherry (or wine), and stir to scrape up any brown, stuck-on bits from the bottom of the pot. Stir in the bone broth (ideally you should have ~6-8 cups’ worth), then toss the garlic back in along with the thyme and bay leaf. BA insists that you bundle these last 3 items together in cheesecloth (for easy removal), but this is a faff and it’s quite easy to just eventually pluck them out using tongs and a sharp eye. Bring the soup to a boil, then reduce the heat to a solid simmer and cook, stirring occasionally, until the liquid has reduced slightly and the flavours have melded together beautifully, ~30 minutes. Remove the garlic, thyme, and bay leaf. Taste and season with salt and pepper as needed.
Preheat the broiler while you prepare the soup. Divide the soup amongst 6 acceptable bowls, filling to as least ¾ full if not more (part of the joy of onion soup is all the bubbling and spilling over the edges that happens). Top each bowl with a suitable-sized slice of bread and 1 slice of each cheese. Place on a rimmed baking sheet (non-negotiable unless you just can’t get enough of cleaning your oven) and broil until the cheese is totally melted and developing lovely browned spots, ~5 minutes. Serve immediately and jubilantly.