Cheddar-Stuffed Black Bean and Mushroom Burgers

Ingredients

• 1 can black beans (14 ounces), drained and rinsed
• 1 10-ounce package cremini (baby bella) mushrooms, sliced
• 1 slice whole-grain bread, toasted
• 1 small onion, chopped
• 2 cloves garlic, chopped
• 1 T balsamic vinegar
• 1 1/2 t ground cumin
• 1/4 t salt
• 1 t black pepper
• 1 egg
• 4 oz sharp cheddar cheese, sliced