This cozy bowl of soup consists of deeply caramelized onions with roasted poblanos swimming in a delicious and flavorful broth that’s topped with gooey cheesy toast. Comfort in a bowl!
I found this recipe on Food and Wine and couldn’t wait to make it with my two freshly picked baby poblanos–the last from my summer garden. This recipe has a different approach to making French onion soup than my normal go-to recipe so I was excited to give it a try. The onions take a lot of time to cook down so make sure to do this recipe when you have lots of time on your hands! The broth was tangy and had a nice depth of flavor, the onions were nicely caramelized and the roasted poblano gave the soup a nice touch of heat and a smokey flavor. We all enjoyed the soup and it paired nicely with the gourmet salad I served it with.
How to Make French Onion Soup with Roasted Poblano
Cook the onions by melting the butter in a large Dutch oven over medium heat. Add the onions, bay leaves, and thyme sprigs then season with sea salt and freshly cracked pepper, to taste. Stir to evenly coat the onions with the butter.
Cover with a lid and cook, stirring occasionally, for 25 minutes, until the onions are translucent and cooked down.
Uncover the Dutch oven and cook, stirring occasionally, until most of the liquid has evaporated and the onions are beginning to stick to the bottom of the Dutch oven, about 35-40 minutes.
Add a splash of water and continue to cook, stirring often (adding more water as needed), until onions are jammy and deeply caramelized, about 40 minutes.
Roast the poblanos while the onions are cooking by preheating the oven to broil with a rack near the top of the oven. Place the poblano peppers on a baking sheet and place and directly under the broiler. Char both sides of the peppers until blackened, about 2-3 minutes per side. Watch carefully.
Remove immediately from the oven and place the poblano peppers in a zip lock bag and seal.
Set aside for 10 minutes then remove all the charred skin from each pepper along with the stem and seeds. Dice into small pieces; set aside in a sealed container until needed.
Make the soup by stirring the balsamic vinegar into the caramelized onions and reduce the heat to medium-low and cook, stirring often, until onions have absorbed the vinegar and are starting to look dry, about 5 minutes. Side Note: This soup is very tangy, use a bit less vinegar if you prefer a less tangy broth.
Dust the onions with the flour and cook, stirring often, for 10 minutes, adding about 2 tablespoons of water at a time as needed to scrape up any brown bits from the bottom of the Dutch oven.
Stir in the broth and bring to a vigorous simmer over medium-high heat. Reduce the heat to medium-low, and simmer, stirring occasionally, for about 30 minutes. Remove and discard the bay leaves and thyme sprigs.
Remove from the heat; stir in roasted poblano then taste the soup and season with sea salt and freshly cracked pepper, to taste, as needed.
Finish the soup by adjusting the oven rack to the upper-middle position. Preheat the oven to broil.
Set heat-safe bowls or crocks on a baking sheet covered in tin foil for easy cleanup. Fill each bowl with soup then top each bowl with 1-2 baguette slices and add some shredded gruyere on top. Broil until well browned and bubbly, about 5-7 minutes. Side Note: My kids prefer that I toast the cheese on the baguette separately so they can dip the cheesy toast into the soup rather than it being on top of the soup. Both ways are delicious!
Cool for a few minutes then serve. Enjoy.