Caramelized Onion Grilled Cheese Sandwiches With Miso Butter 2.000

Tom McCorkle for The Washington Post; food styling by Lisa Cherkasky/The Washington Post

Weeknight Vegetarian Sep 15, 2019

These indulgent sandwiches get a nice tang from whole-grain mustard and a big hit of umami from the miso and the caramelized onions. Grilled cheese for dinner: Why not?


When you scale a recipe, keep in mind that cooking times and temperatures, pan sizes and seasonings may be affected, so adjust accordingly. Also, amounts listed in the directions will not reflect the changes made to ingredient amounts.

Tested size: 2 servings

  • 1 tablespoon extra-virgin olive oil
  • 1 large yellow onion (1 pound), thinly sliced
  • 1/8 teaspoon kosher salt
  • 1 tablespoon rice vinegar, preferably unseasoned
  • 3 tablespoons unsalted butter, at room temperature (may substitute vegan butter, such as Earth Balance)
  • 2 teaspoons white or dark miso paste
  • 1 tablespoon whole-grain mustard
  • 4 slices good-quality sandwich bread
  • 4 ounces grated Gruyère cheese (1 cup; may substitute vegan shredded cheese, such as Violife or Daiya)
  • Cornichons (a.k.a. gherkins), for serving (optional)


In a large skillet over medium-high heat, heat the oil until shimmering. Add the onion and salt and cook, stirring often, until they start to soften and brown, 5 to 6 minutes. Reduce the heat to medium-low and cook, stirring occasionally, until the onions are deeply browned and sticky, 30 to 45 minutes. Stir in the vinegar. Transfer the onions to a small bowl.

In a small bowl, mix 1 tablespoon butter with the miso paste and mustard. Spread one side of each bread slice with the remaining 2 tablespoons butter. Spread the other sides with the miso butter.

Return the skillet to medium-low heat. Place two of the bread slices, plain-buttered-side down, in the skillet. Divide the cheese and onions evenly between them and top with the other bread slices, plain-buttered-side up. (You want the miso butter on the inside of the sandwiches.) Cook until the bread is golden brown, 5 to 7 minutes. (Resist the urge to press the sandwich with a spatula.) Flip the sandwiches over and cook on the other side until the bread is golden brown and the cheese is melted, 5 to 7 minutes. Transfer to plates and serve with cornichons, if desired.

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Recipe Source

Adapted from “Umami Bomb” by Raquel Pelzel (Workman, 2019).

Tested by Joe Yonan.

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