Mushroom Swiss Burgers Recipe

Ingredients

• 1 ½ cups cooked black beans, divided
• 2 cups roughly chopped fresh portobello mushrooms
• 1 ½ cups panko (Japanese bread crumbs)
• 2 large eggs, lightly beaten
• 2 cloves garlic, minced
• 1 teaspoon kosher salt
• ½ teaspoon ground black pepper
• 4 tablespoons unsalted butter, divided
• 1 small red onion, thinly sliced
• 4 slices Swiss cheese
• 4 sesame seed buns
• Fresh arugula, to serve