Mushroom Swiss Black Bean Burger Recipe with Plantain Buns

Name: Mushroom Swiss Black Bean Burger Recipe with Plantain Buns
Ingredients: 2 tablespoons olive oil (divided); 1 yellow onion (diced); 2 cloves garlic (minced); 1 cup baby bella mushrooms (chopped, divided); 2 cans black beans ((15-ounces) rinsed and drained); 1 egg; 1/2 teaspoon cumin; 1/2 teaspoon dried oregano; 1/2 teaspoon smoked paprika; 2 teaspoons Worcestershire sauce; 1 cup bread crumbs; Salt and pepper to taste; 4 slices Swiss cheese; 12 Tostones (Twice Fried Plantains) (cooked)