By Vallery Lomas
Published April 9, 2024
- Total Time
- 1 ¾ hours
- Prep Time
- 15 minutes
- Cook Time
- 1 ½ hours
- Rating
- 4(108)
- Notes
- Read community notes
Fill store-bought brioche buns with jammy, caramelized onions and melted Gruyère, for satisfying little sandwiches that make a perfect soup companion or a cozy, comforting meal. Caramelizing the onions takes some time but very little effort, and coaxing out the ingredient’s sweet side is well worth it. The butter used to caramelize the onions adds flavor, and the extra-virgin olive oil allows the onions to tolerate higher heat without burning. (However, if you find the onions are browning unevenly, turn the heat down to low.) Prepare a big batch of these balsamic caramelized onions ahead of time and lunch can be on your plate in 10 minutes.
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Ingredients
Yield:4 servings
- 2tablespoons extra-virgin olive oil
- 1 to 2tablespoons butter (unsalted or salted)
- 2large yellow onions, thinly and uniformly sliced (about 8 cups), see Tip
- Salt and pepper
- 1tablespoon balsamic vinegar
- 2½ cups/8 ounces shredded Gruyère
- 4small brioche buns, cut in half crosswise
Ingredient Substitution Guide
Nutritional analysis per serving (4 servings)
606 calories; 32 grams fat; 15 grams saturated fat; 0 grams trans fat; 12 grams monounsaturated fat; 3 grams polyunsaturated fat; 58 grams carbohydrates; 7 grams dietary fiber; 19 grams sugars; 25 grams protein; 1205 milligrams sodium
Note: The information shown is Edamam’s estimate based on available ingredients and preparation. It should not be considered a substitute for a professional nutritionist’s advice.
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Preparation
Step
1
Caramelize the onions: Heat the olive oil and 1 tablespoon butter in a Dutch oven or large, heavy skillet over medium. Once the butter melts, add the sliced onions and a large pinch of salt. (If your onions are particularly large, you may need another tablespoon butter to thoroughly moisten them.) Cook, stirring occasionally, until the onions are softened and translucent, 7 to 10 minutes.
Step
2
Reduce the heat to medium-low and continue cooking, stirring occasionally, until the onions are deep brown all over, 1 hour to 1 ¼ hours total, reducing the heat to low if they are browning unevenly. (If the onions start to stick to the bottom of the pan and burn, reduce the heat to low and add the balsamic vinegar, stirring to deglaze the browned bits from the bottom of the pan.) When the onions are caramelized, stir in the balsamic vinegar if you haven’t already added it. Remove from heat.
Step
3
Heat the oven to broil (on low, if possible). Place the halved brioche buns open on a sheet pan. Divide the cheese evenly among each bun half and broil until melted, 3 to 4 minutes. Remove the buns from the oven and sprinkle with ground black pepper. Add caramelized onions (about 2 tablespoons) to the bottom half of each bun. Sandwich the two halves and serve.
Tip
- Onions that are sliced uniformly will brown more evenly, and onions that are sliced thinly will caramelize faster.
Ratings
108
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Cooking Notes
Christa
Here's a timesaving tip tor an easy and speedy meal: make Ali Slagle's caeamelized onions ahead of time and freeze them, as I did this past winter.
David Hawkins
According to Kenji López-Alt, adding oil to butter does nothing to reduce the risk of burning the butter. Another myth that Julia Moskin might have addressed.
Jeff B
Have not made this, love French onion soup. I'd try this with a small smash burger for protein and umami. As written, caramelized onions with balsamic on a brioche bun is much too sweet for my taste. Even with gruyere cheese. I'm not a sweet fan unless it is dessert.
Renee
Good to know adding oil won't help to stop butter from burning though I'd not expect a low-smoking-point oil like olive to help in that regard anyway. Maybe it's just a nice combination of flavors - olive oil and butter?
John Drake
Not a complaint (it looks good), but you've recreated the Krystal/White Castle burger without the patty.
Janet H.
Made the recipe as written, but found that the small amount of vinegar wasn't quite enough liquid to deglaze the pan, so I added an equal amount (1 tbsp) of water. (I imagine this can easily be repeated if necessary, with a few more minutes in the pan to cook off the extra liquid - an old French Onion Soup technique). These are so good, that they upstaged the soup I served them with. What a great idea.
T
Adding oil to butter won't stop the milk solids in the butter from burning.If you want a buttery taste but high heat cooking, use ghee (clarified butter).
Annie
Sounds like a perfect option to add to burger night for vegetarian friends. Any suggestions on interesting accompanying dishes instead of things like fries?
Jeff B
Have not made this, love French onion soup. I'd try this with a small smash burger for protein and umami. As written, caramelized onions with balsamic on a brioche bun is much too sweet for my taste. Even with gruyere cheese. I'm not a sweet fan unless it is dessert.
David Hawkins
According to Kenji López-Alt, adding oil to butter does nothing to reduce the risk of burning the butter. Another myth that Julia Moskin might have addressed.
Christa
Here's a timesaving tip tor an easy and speedy meal: make Ali Slagle's caeamelized onions ahead of time and freeze them, as I did this past winter.
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