I hesitate to call this French Onion soup because I’ve made 2 pretty big changes to the classic. First, I roasted mushrooms and placed them on top of the baguette slices, under the cheese, before finishing under the broiler. And second, I added miso paste to the broth before simmering to add a little more depth and complexity. The classic will always be delicious, but I think I like this version a little bit more.
Equipment
Here’s everything you need to make my roasted mushroom French onion soup at home:
- large, thick-bottomed pot or Dutch oven
- chef’s knife
- cutting board
- sheet pan
- oven-safe soup ramekins
- grater
- bread knife
- fine mesh sieve
Get the full ingredients list and instructions below!
Cooking Tips
- Caramelized onions can be a pain the the a— but I think I’ve got a pretty good method that will help save time. I add all the sliced onions to the pot, season with 1 tsp salt and cook on medium-high — this will sweat out the onions and evaporate any water they produce quickly. Once they’ve reduced in volume by about half, I turn the heat to medium and continue cooking, stirring only occasionally to promote browning. Next, I set about 1 cup of water beside the pot and add 1-2 tbsp whenever I see the onions browning too quickly or scorching on the bottom of the pan. Adding the water, but keeping the heat on medium (instead of low, as most recipes suggest) will promote browning, but keep the onions soft so they don’t fry and become crispy. I find this method saves about 10 minutes of cook time and produces deeply caramelized onions.
- Most French Onion recipes call for sherry, but it’s not the easiest (or cheapest) to find. Instead, I call for sherry vinegar, which is a little easier to source, lasts longer, and is more likely to be used in every day cooking. Incorporate it into your vinegar rotation and take note of how it changes the flavour profile of your dishes! If you don’t have sherry vinegar, balsamic is a great option — use the same amount (2 tbsp) as called for below!
Ingredients
Method
- Thinly slice 5 sweet onions. Heat a thick-bottomed pot, or Dutch oven, on medium. Add 2 tbsp butter and 1 tbsp olive oil. When the butter foams, add onions and season with 1 tsp salt. Increase heat to medium-high and let the onions cook, stirring occasionally, until they've reduced in volume by about half. Fill a measuring cup with 1 cup water, and place next to the pot. Reduce heat to medium, and continue cooking like this, adding a tbsp or two of water as needed, until they are deeply caramelized, about 35 minutes.
- Preheat oven to 400°F and line a baking sheet with parchment. Meanwhile, tear 600g oyster mushrooms into bite-sized pieces and dice 4 cloves garlic. Transfer the mushrooms to the baking sheet and cover with a generous pinch of salt and 2 tbsp olive oil. Toss to coat, then bake until golden and crispy, about 20 minutes.
- Back in the pot, the onions should be about half-way finished. Add the garlic and continue cooking until deeply caramelized. Deglaze with 2 tbsp sherry vinegar and cook until the vinegar mostly evaporates and the aroma is more sweet than vinegar-y. Add in 5 sprigs of fresh thyme and 2 bay leaves. Cover with 4 cups beef broth and 1 cup water. Add 1 tbsp miso to a small fine mesh sieve. Using a spoon mix the miso into the broth, pushing it through the sieve first to prevent clumping. Bring to a simmer and cook for 20 minutes.
- Meanwhile, grate 100g Gruyère and cut 8 slices from 1 fresh baguette. Remove the mushrooms from the oven and set aside to cool. Place a rack in the upper third of oven and turn broil to high.
- Transfer soup to oven-safe ramekins, top with 2 baguette slices, a handful of roasted mushrooms and enough grated Gruyère to generously cover the top. Broil until completely melted and starting to brown all over, about 5 minutes.
- Serve hot with more fresh thyme sprinkled on top.