Hearty Black Bean Burger Bliss

Ingredients

• 1 can • black beans, drained and rinsed
• 1/2 cup • breadcrumbs
• 1/4 cup • finely chopped onion
• 1/4 cup • finely chopped bell pepper
• 2 cloves • garlic, minced
• 1 tsp • cumin
• 1 tsp • chili powder
• • Salt and pepper to taste
• 1 • egg (optional, for binding)
• 4 • burger buns
• 1 • avocado, sliced
• • Lettuce leaves
• 1 large • tomato, sliced
• • Chipotle mayo (mix of mayonnaise and chipotle pepper in adobo sauce)