Years ago, my husband and I used to go to the symphony. This was before one of us (I won't say who) turned 40, disqualifying us from the Boston Symphony's young subscribers program. It was also before we had to think about finding a babysitter for a night out.
Rather than rushing through dinner to make the show, we often had a late dinner after the concert. One of our favorite places, Brasserie Jo, was a short walk from Symphony Hall. Since it was after 10 o'clock by the time we walked in, we'd generally skip the steak frites and roast chicken. Instead, especially in the dead of winter, we'd order the French onion soup. Or, as they called it, making it sound so much fancier, the onion soupe gratinée.
It was perfection. The soup was rich and flavorful, full of sweet, silky onions. It was topped with a slice of crisp baguette. But the best part, the part that I still think about years later, was the luscious cheese, melted and bubbling, all over the top. You'd dip your spoon in and pull it up, up, up, higher and higher until you had to go in for a bite, twirling it around your tongue like a strand of spaghetti.
I wasn't sure you could replicate that experience at home. But given how many years it's been since our last trip to Brasserie Jo (or the symphony for that matter), I figured I had to give it a try. And you know what? It worked.
Now I'd love an evening at the symphony, followed by a cozy meal at a brasserie. But when that's not in the cards, at least I can have the soup.
Cut the onions into thin slices.
Put the onions in a Dutch oven with thyme and salt.
Cook for 30 to 45 minutes until the onions are dark and sticky. Take your time. This is where all the flavor comes from.
Stir in the vinegar.
Add the chicken and beef broths. Bring to a boil and let it simmer.
While the soup is cooking, bake the bread until it hardens. This will help it stay crisp in the soup.
Shred your cheese.
When you're ready to eat, ladle some soup into oven-safe bowls. Top with one or two baguette slices and some cheese (be generous)!
Bake until the cheese melts. Then turn on the broiler for a minute or two until the cheese bubbles and browns in spots.
French Onion Soup
Recipe slightly adapted from The America's Test Kitchen Family Cookbook
2 Tbsp unsalted butter
5 medium (3 lbs) red onions, halved and sliced thin
2 tsp minced fresh thyme
1/4 cup balsamic vinegar
6 cups low-sodium chicken broth
1 3/4 cups low-sodium beef broth
2 bay leaves
1 baguette, sliced 1/2-inch thick
8 ounces Gruyere cheese, shredded (you can also use mozzarella or any cheese that melts well)
1. Preheat the oven to 350 degrees and adjust the oven rack to the middle position.
2. Melt the butter in a large Dutch oven over medium heat. Add the onions, thyme, and 1/2 teaspoon salt. Cook, stirring occasionally, until the onions are dark and sticky, about 30 minutes (it took me closer to 45 minutes).
3. Stir in the vinegar and scrape the browned crust from the pot.
4. Stir in the chicken broth, beef broth, and bay leaves. Bring to a simmer and cook fro 20 minutes. Season with salt and pepper to taste and discard the bay leaves.
5. While the soup is simmering, prepare the bread. Lay the slices on a baking sheet. Bake for about 10 minutes, turning once, until the bread has hardened. This will help it stay crisp when you put it on the soup.
6. When the bread is out of the oven, increase the heat to 450 degrees.
7. Arrange oven-safe soup bowls on a rimmed baking sheet and ladle the soup into them. Top each bowl with 2 baguette slices. Sprinkle each with 1/4 cup of the cheese.
8. Bake for 5 minutes. Then turn on the broiler and heat for 1 to 2 minutes, until the cheese begins to bubble and brown in spots. Watch carefully so that the cheese doesn't burn. Serve hot.