All the flavors of French onion soup are piled high on a tender portobello mushroom and sandwiched between English muffins. These are the ultimate meatless burgers!
Preheat the broiler. Line a rimmed baking sheet with aluminum foil.
Melt the butter in a medium skillet over medium-low heat. Add the sliced onions, 1 tablespoon fresh thyme or 1 1/2 teaspoons dried, 1/2 teaspoon kosher salt and a few grinds of pepper. Cook, stirring occasionally, until the onions are deep golden brown and caramelized, about 15 minutes. If the skillet gets too brown, add 2 tablespoons water and scrape the brown bits from the bottom of the skillet with a wooden spoon; continue to cook until all the water has evaporated. Add 1 tablespoon of the Worcestershire and stir until completely absorbed, about 1 minute more.
Meanwhile, place the muffins or buns on the prepared baking sheet and broil until toasted and browned along the edges, 1 to 2 minutes. Set aside for serving.
Put the mushroom caps, gill-side up, on the same baking sheet. Broil until they release their juices and soften slightly, about 6 minutes. Flip the mushrooms, brush the tops with the oil and season with the garlic salt. Broil until lightly browned and the juices have cooked off, about 6 minutes more. Top each mushroom with 1/4 cup cheese, then return to the broiler until the cheese melts, 1 to 1 1/2 minutes.
While the mushrooms are broiling, stir together the mayonnaise, garlic, remaining 1 teaspoon fresh thyme or 1/2 teaspoon dried thyme and 1 teaspoon Worcestershire in a small bowl until smooth. Season with a pinch of kosher salt and pepper. Spread on the inside of the toasted muffin or bun tops. Place 1 portobello mushroom on each muffin or bun bottom. Layer with the caramelized onions and crispy fried onions, then close the burgers and serve.
Tools You May Need
Tools You May Need
Price and stock may change after publish date, and we may make money off
these links.
By entering your email address, you agree to our Terms of Use
and acknowledge the Privacy Policy.
Food Network and
its affiliates
may use your email address to provide updates, ads, and offers.
To withdraw your consent or learn more about your rights, see the
Privacy Policy.