Ingredients
For the burgers:
- 2 tablespoons olive oil, divided
- ½ yellow onion, finely diced
- 8 ounces cremini mushrooms, finely chopped
- 3 cloves garlic, minced
- 1 teaspoon ground cumin
- ½ teaspoon smoked paprika
- ½ teaspoon kosher salt
- ¼ teaspoon freshly ground black pepper
- 1 (15-ounce) can black beans, drained and rinsed
- 1 (15-ounce) can garbanzo beans, drained and rinsed
- 1 tablespoon ground flaxseed mixed with 3 tablespoons water (flax egg)
- 1 large egg
- ½ cup panko breadcrumbs
- 1 tablespoon soy sauce or tamari
For serving:
- 1 head iceberg lettuce, leaves separated into cups
- 1 ripe avocado, sliced
- 1 large tomato, sliced
- ½ red onion, thinly sliced
- Cucamelon relish or pickles of your choice
- Spicy mayo (mayonnaise mixed with chili paste to taste)
Instructions
Cook the vegetables:
- Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add the diced onion and cook, stirring occasionally, until softened and translucent, about 4-5 minutes. Add the chopped mushrooms, garlic, cumin, smoked paprika, salt, and pepper. Cook for 10-12 minutes, stirring only every few minutes, until the mushrooms are deeply golden, all of the moisture has cooked off, and they smell intensely earthy and nutty. The pan should look almost dry. Transfer to a large mixing bowl and let cool for 5 minutes.
Make the burger mixture:
- Preheat the oven to 375°F. Line a baking sheet with parchment paper and lightly oil it.
- Add the black beans and garbanzo beans to the bowl with the mushroom mixture. Use a potato masher or fork to smash roughly — you want about half the beans mashed and half left chunky for texture. Stir in the flax egg, regular egg, panko breadcrumbs, and soy sauce. The mixture should hold together when you squeeze a handful — if it feels too wet, add another tablespoon of panko. If too dry, a splash of water.
Bake the patties:
- Divide the mixture into 6 equal portions and shape into patties about ¾-inch thick. Place them on the prepared baking sheet. Bake for 15 minutes, then carefully flip and bake for another 10 minutes. They should feel firm to the touch and have a dry, slightly cracked surface. This step is what keeps them from falling apart in the pan.
Pan-fry and serve:
- Heat the remaining 1 tablespoon of olive oil in a large skillet over medium-high heat. When the oil shimmers, add the baked patties and cook for 2-3 minutes per side, until a deep golden-brown crust forms. You should hear a steady sizzle — if it is quiet, the pan is not hot enough. Serve immediately in crisp iceberg lettuce cups with avocado, tomato, red onion, cucamelon relish, and a generous drizzle of spicy mayo.