Most veggie burgers are an agglomeration of indiscriminate scraps bound with mashed beans or overcooked grains and marked by a generic “spiced” flavor. Some are more premium than others, or more meat-like, but none have gone so far as to upend the menu item in the way that New York’s Shake Shack has. Most meatless burgers connote healthfulness; Shake Shack simply made something without meat, served it on a hamburger bun and called it a veggie burger. The result — a deep-fried, cheese-stuffed portobello cap — is so amply filling and immensely crave-able, you won’t miss the beef.
4 4-inch portobello mushroom caps
1/4 cup canola oil, plus more for frying
1/2 teaspoon kosher salt
1/8 teaspoon freshly ground black pepper
1 1/2 cups flour
2 cups panko bread crumbs
1 1/2 cups grated muenster cheese
1/2 cup grated cheddar
1/2 teaspoon minced onion
1/8 teaspoon minced garlic
1/4 teaspoon flour
1 egg yolk
1 pinch cayenne
4 tablespoons ShackSauce
4 potato buns, toasted
4 piece green leaf lettuce
8 1/4-inch slices ripe plum tomato
1. For the mushroom caps, preheat the oven to 375°F. Put mushroom caps on a medium baking pan. Rub caps all over with the oil, then season both sides with the salt and pepper. Arrange mushrooms, gill-side down, in a single layer and roast until tender, 30 to 35 minutes. Remove from the oven and set aside to cool. Slice mushrooms in half horizontally.
2. Put the flour in a wide dish, beat the eggs in another wide dish, and put the panko in a third wide dish and set aside.
3. For the filling, mix together the muenster and cheddar cheeses, onion, garlic, flour, egg yolk, and cayenne in a medium mixing bowl.
4. Shape the filling into 4 equal disks, 1/2 inch smaller in diameter than the mushroom caps. Place cheese disks on gill side of each mushroom cap, cover with other half of cap, cut side down, and gently press together to secure the filling.
5. Dredge the stuffed mushroom caps in the flour, then dip in the beaten egg, coating them completely, then dredge in the panko. Set prepared mushrooms on a plate and refrigerate while heating the oil to deep-fry them.
How to Make ShackSauce
1. Add 1/2 cup Hellman’s mayonnaise, 1 tablespoon Dijon mustard, 3/4 teaspoon Heinz ketchup, 1/4 teaspoon kosher dill pickling brine and a pinch of cayenne pepper to a small mixing bowl.
2. Stir until well combined. Sauce will keep, covered, in the refrigerator for up to one week.
6. To cook the mushroom burgers, pour the oil into a deep, wide pot to a depth of 3 inches. Heat over medium heat until the oil reaches a temperature of 350°F on a candy thermometer. Deep-fry the prepared mushrooms, one or two at a time, until golden brown and crisp all over, about 3 or 4 minutes. Transfer mushrooms with a slotted spoon to drain on paper towels. Season with salt.
7. Spoon the ShackSauce onto each top bun. Add a piece of lettuce and two slices of tomato.
8. Transfer the mushroom burgers to the prepared buns.
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The recipe above appears in Shake Shack: Recipes & Stories, by Randy Garutti and Mark Rosati, published by Clarkson Potter, an imprint of Penguin Random House. Buy Now: $16