Ingredients
For the Shroom Burgers
- 4 large portobello mushroom caps, stems removed
- Olive, vegetable, avocado, or canola oil, for roasting and frying
- 1 teaspoon kosher salt
- 1 1/2 cups plus 1 teaspoon all-purpose flour, divided
- 4 large eggs, divided
- 2 cups panko breadcrumbs
- 1 1/2 cups shredded mozzarella cheese
- 1/2 cup shredded cheddar, Gruyère, Monterey Jack, or another good melting cheese
- 1/4 teaspoon onion powder
- 1/4 teaspoon garlic powder
- 4 hamburger buns
For the Faux ShackSauce
- 1/2 cup mayonnaise
- 1 tablespoon Dijon mustard
- 1 teaspoon ketchup
- 1 teaspoon dill pickle juice
- Pinch of cayenne pepper, optional
Use vegan mayonnaise if you’d like to make the sauce dairy-free.
Topping Ideas
- 1 ripe tomato, sliced
- 1/2 ripe avocado, sliced
- 4 pieces romaine or other crisp lettuce
Instructions
1. Roast the Mushrooms
Preheat the oven to 375°F.
Place the portobello caps on a parchment-lined baking sheet. Rub them with oil and season both sides with salt.
Place the mushrooms gill-side down and roast for 30–35 minutes, or until slightly golden. Remove from the oven and let them cool enough to handle.
2. Build the Cheese Center
Carefully slice each mushroom cap horizontally through the middle, aiming to make two even halves.
In a medium bowl, combine the mozzarella, cheddar, onion powder, garlic powder, and 1 egg.
Divide the cheese mixture into 4 portions and shape each into a disk slightly smaller than the mushroom caps.
Place one cheese disk between two mushroom halves and gently press together to secure. Refrigerate until ready to bread.
3. Set Up the Breading Station
Place the remaining flour in a deep bowl or pie plate.
In a second bowl, whisk the remaining 3 eggs.
Place the panko breadcrumbs in a third bowl.
Working one at a time, coat each stuffed mushroom in flour, then the beaten egg, and finally the panko. Press the breadcrumbs gently onto the mushroom so they stick.
4. Fry Until Golden
Add about 1/2 inch of oil to a large sauté pan or cast-iron skillet. Heat over medium-high heat until the oil reaches about 350°F.
Carefully add the breaded mushrooms and fry for 3–4 minutes per side, or until golden brown and crisp.
Transfer to a paper towel-lined plate to drain.
5. Stir Together the Sauce
Add the mayonnaise, Dijon mustard, ketchup, pickle juice, and cayenne to a small bowl.
Stir until smooth and combined.
6. Build Your Burger
Place a crispy shroom burger on the bottom half of a bun.
Top with avocado, tomato, lettuce, and a spoonful of the sauce. Add the top bun and serve while warm.
Notes
- Keep the mushrooms even: Slice horizontally as evenly as possible so the cheese stays tucked inside.
- Chill before breading: Refrigerating the stuffed mushrooms helps them hold their shape while you coat them.
- Get the oil hot: Oil around 350°F helps the panko become crisp without leaving the coating overly greasy.
- Don’t crowd the pan: Fry in batches if needed so the oil temperature stays steady.
- Press on the panko: A gentle press helps the crispy coating adhere to the mushrooms.
