This is the best French Onion Soup Gratinée I’ve ever had, including some from very expensive restaurants.
The trick is that French Onion Soup Gratinée is supposed to be onion soup. Not canned beef broth with some onions, soggy bread and cheap cheese. This recipe extracts nearly every possible flavor variation from the onions, via multiple deglazings and several different levels of cooking.
It has a beautifully deep, rich flavor with layers of onion taste profiles ranging from deep and sweet, to slightly sharp with a little bite. The sherry provides a touch of brightness and the thyme and bay leaf provide a “green” note.
The “trick” (not really a trick, but also not obvious) is that a lot of the soup’s deep, rich flavor comes from caramelization of the onions. Traditionally, this is done just once after sauteing the onions, however there’s no reason to stop there. The onions are still packed with potential flavor, and we’re going to get every bit of it!
This recipe calls for sauteing a batch of onions until they’re nearly gone, then deglazing the pan with a little water. Then we do it again. And again, creating a deep, rich onion broth with huge flavor. The last batch of onions doesn’t get cooked quite as much, which creates an additional layer of flavor (a little sharp with a distinct onion flavor) which contrasts nicely with the rich, slightly sweet flavor in the broth.
The garlic toast adds another layer of flavor as well as a crunchy texture, the herbs and sherry brighten it up, and selecting the right cheese makes everything just about perfect.
NB. I’ll never say anything is “perfect” because that always leaves room for improvement. 
The recipe takes a little work, but isn’t complicated, and as Alton Bron says: “Your patience will be rewarded”
| Ingredients: | ||
| 5 | Lbs | Yellow Onions, peeled, cut pole-to-pole, then 1/4 inch thick |
| 4 | Tablespoons | Unsalted Butter, cut into chunks |
| Water | ||
| 4 | Cups | Low Sodium Chicken Broth |
| 2 | Cups | Beef Broth |
| 1/2 | C | Dry Sherry. (not “Cooking Sherry”) This should be good enough to drink. Don’t be cheap here. |
| 6 | Sprigs | Fresh Thyme |
| 1 | Bay Leaf | |
| Kosher Salt and Fresh Ground Pepper | ||
| 1 | Lb | Real Gruyere Cheese, aged 10-12 months. Taste this before you buy it. It should be a little earthy but not overpowering. |
| 1 | Baguette, with 12 slices one half an inch thick cut from it | |
| Olive Oil | ||
| 3 | Cloves | Garlic |
Cooking:
- Grate the cheese place in the refrigerator.
- Heat a large thick-bottomed pot on medium high, add a chunk of butter and about a quarter of the onions. Sprinkle on a pinch salt and saute until completely caramelized and very dark brown. When the bottom of the pot is covered with fond, deglaze with a little water. Repeat until the onions are almost gone and there is a ton of rich, dark, brown fond in the bottom of the pot. Stir as necessary, and adjust the heat to prevent burning.
- Add another chunk of butter, another quarter of the onions and repeat the above process, but don’t cook quite as dark.
- Repeat for all four batches of onions. On the last batch, cook until the onions are softened, but not completely wilted, and deglaze with sherry.
- Add all the other ingredients except the salt and pepper and simmer for 30 minutes.
- Remove the bay leaf and the thyme, and add salt and pepper to taste. If it’s a little dull tasting, you can add more sherry to brighten it up.
- At this point, the soup can be refrigerated for up to several days if you wish. I typically store it in a vacuum sealer bag to prevent it from picking up flavors from the refrigerator.
Serving:
- If chilled, reheat the soup, but don’t boil!.
- Taste it and see if it needs a little more salt, pepper or sherry. Or not.
- Take all 12 slices of baguette, trim to fit the crocks, then place the bread on a tray and broil until golden brown, then turn over and broil the other side as well. this can also be done in a toaster oven.
- Brush one side of each slice with olive oil then rub a garlic clove over the same side. You can usually get 4 slices from each clove of garlic. The olive oil prevents the toast from becoming soggy too quickly, and I have no explanation for the garlic, except that I like the way it tastes and smells in the bowl and makes the crouton more intereting.
- Preheat your broiler on high. Ladle the soup into oven-proof crocks, leaving about a 1/2 inch of space on the top.
- Lay the garlic toast over the soup, garlic and olive oil side down, cover with grated cheese and broil until the cheese is browned to about the same level as a good pizza.
- Serve immediately with the remaining baguette and butter on the side.
Serves 6