Haricot Verts with Caramelized Onions

4.89 from 18 votes
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Haricot verts with mushrooms and caramelized onions are a crunchy and delicious side dish. Savory portabella mushrooms & pearl onions pack extra flavor!

Haricot verts with mushrooms and caramelized onions

Have you met the string beans French cousin, haricot verts? Kinda like the new hot foreign exchange student in high school, these long, slender and crisp beauties are a little sleeker and sexy than your typical green bean. This vegetable along with mushrooms and caramelized onions will steal the dinnertime show!

There is no better savory combo than onions and mushrooms. The magic to the dish is slowly allowing the baby pearl onions to caramelize in the pan over low heat. This enables the deep sweet flavors to be teased out of the onions.

top down view of haricot verts with mushrooms and caramelized onions

I use thin slices of baby portabella mushrooms (or hearty brown mushrooms) because they have better flavor than white button mushrooms, just my opinion. Mushrooms seem to have this innate deep salty flavor once cooked that adds so much richness to any dish, can you tell I’m a fungi fan? Super nerd, ha!.

To finish off the vegetables, I quickly blanch the haricot verts in salted super rapid boiling water for a quick 3 to 4 minutes, or less, testing to see if they have a nice crunch each minute. I then immediately plunge the beans in ice cold water to stop the cooking process and keep them bright green.

close up of haricot verts with mushrooms in a bowl

Once all of the beans, umami mushrooms and sweet caramelized onions are combined with fresh chopped thyme, garlicky shallots and sprinkled with salt and pepper, it’s ready to chow down.

So fresh, healthy and satisfying! I like to serve this green bean dish as a side with my herb brined roasted chicken recipe with some mashed red potatoes, yummy! If you have started an insatiable green bean craving, give my citrus green beans with almonds recipe a try!

What is the trick to caramelizing the pearl onions?

First off, the real question is why should caramelize onions? It’s because when it’s done right, they bring a sweet, umami (savory) punch to any dish and make it 10x better! It requires a little extra time and patience (at least 30 minutes), but well worth the wait. Add a thin layer of oil (butter burns too quick) over medium-low heat; the onions will burn on high heat so turn it down if they are browning too quickly. You want to have a single layer of onions (cut side down first) in the pan, so it does not steam, the goal is to get the moisture to evaporate and the pan just hot enough to turn those sugars in the onions to caramelize into brown pigments and flavor. Let them slowly cook, trying not to stir too often, so they get maximum contact with the pan surface to coax out those flavors. The onions should be a rich brown, very soft, yet not mushy and have a delicately sweet taste.

Haricot Verts with Caramelized Onions

Haricot verts with mushrooms and caramelized onions are a crunchy and delicious side dish. Savory portabella mushrooms & pearl onions pack extra flavor!
4.89 from 18 votes
Prep Time15 minutes
Cook Time50 minutes
Total Time1 hour 5 minutes
Servings 2 servings
Course Side
Cuisine French


  • 2 tablespoons olive oil, divided
  • 8 ounces pearl onions, peeled (halved if large), 2 cups
  • 12 ounces haricot verts
  • 3 tablespoons unsalted butter, clarified butter or ghee, divided
  • 4 ounces portabella mushrooms, or brown, ¼-inch slices
  • ¼ cup shallots, minced
  • 1 tablespoon thyme leaves, chopped fresh
  • ½ teaspoon kosher salt, or sea salt
  • teaspoon black pepper
  • 2 tablespoons vegetable broth, or chicken broth


  • Heat 1 tablespoon of olive oil in a large frying pan over medium heat. Add onions and cook, without moving until golden brown (reduce heat to medium-low if they get too dark too fast). Carefully turn onions over and let them cook until deeply golden on both sides and tender, about 30 minutes total. Set aside.
  • Fill a large bowl with ice water, set aside. Bring a pot of generously salted water to a boil. Cook beans until bright green and tender, 3 to 4 minutes. Drain and add to the ice water, cool for at least 5 minutes. Drain well and set aside.
  • Heat remaining 1 tablespoon olive oil in a medium frying pan over medium-high heat. Add mushrooms; reduce heat to medium and cook, occasionally stirring until mushrooms release all their liquid and start to brown, about 6 minutes.
  • Add remaining 2 tablespoons butter to the pan. Once that melts and begins to sizzle, add shallots, thyme, salt, pepper, and reserved caramelized onions. Cook, stirring gently until shallots have softened. Add broth and bring to a simmer and cook for about 2 minutes until the stock is reduced and absorbed into the mixture.
  • Heat 1 tablespoon of butter in a large frying pan over medium heat. Add beans and rewarm about 5 minutes.
  • Transfer warmed beans to a large platter or bowl. Pour mushroom mixture over the center and serve immediately.

Nutrition Facts

Serves: 2 servings
Calories 424kcal (21%)Carbohydrates 32g (11%)Protein 8g (16%)Fat 32g (49%)Saturated Fat 13g (65%)Polyunsaturated Fat 2gMonounsaturated Fat 10gCholesterol 48mg (16%)Sodium 747mg (31%)Potassium 915mg (26%)Fiber 7g (28%)Sugar 12g (13%)Vitamin A 2150IU (43%)Vitamin C 35.5mg (43%)Calcium 110mg (11%)Iron 2.7mg (15%)

Percent Daily Values are based on a 2000-calorie diet. All nutritional information is based on estimated third-party calculations. Each recipe and nutritional value will vary depending on the brands you use, measuring methods, and portion sizes per household.

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Jessica Gavin

I'm a culinary school graduate, cookbook author, and a mom who loves croissants! My passion is creating recipes and sharing the science behind cooking to help you gain confidence in the kitchen.

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  1. Kristina Beville says

    The flavor profile on these were amazing! I switched the Pearl Onions and Shallots out for Leeks (Still learning online shopping—I ended up with SO MANY) and fresh thyme for dried (did not have fresh)… These paired very well with game meat (Red Meat). Thank you so much! Post COVID meal definitely brought some soul back into me 🙂

    • Jessica Gavin says

      I’m so happy to hear that cooking is been a great outlet for you. Thank you for making the haricot verts recipe!

  2. Kristen says

    Just made these tonight and they were delicious! Even my kids loved the caramelized pearl onions!! Thank you for sharing a delicious recipe and easy to follow steps!