Really Awesome Black Bean Burgers Recipe

Name: Really Awesome Black Bean Burgers Recipe
Ingredients: 2 (15 ounce) cans black beans, rinsed and drained; 4 tablespoons vegetable oil, divided; 1 medium onion, finely chopped (about 1 cup); 1 large poblano pepper, finely chopped (about 1 cup); 3 medium cloves garlic, minced; 1 chipotle chili in adobo sauce, finely chopped, plus 1 teaspoon sauce; 3/4 cup roasted cashews; 1/2 cup finely crumbled feta or cotija cheese; 2 tablespoons mayonnaise; 1 whole egg; 3/4 cup panko bread crumbs; Kosher salt and freshly ground black pepper; Cheese as desired, such as pepper jack, cheddar, muenster, or Swiss (optional); 6 to 8 hearty hamburger buns, toasted; Condiments as desired, such as Chipotle Mayonnaise, ketchup, mustard, or mayonnaise (optional); Toppings as desired, such as shredded lettuce, sliced onions, and pickles (optional)