Sweet Potato and Black Bean Burger

Ingredients

• 1 small red onion, thinly sliced
• 1/2 cup rice wine vinegar
• 2 Tbsp Better Than Bouillon Seasoned Vegetable Base
• 1/2 tsp granulated sugar
• 1/3 cup walnuts
• 2 cloves garlic
• 1/2 lb sweet potatoes, cooked and mashed
• 1 can (19 oz) black beans, drained and rinsed
• 1 tsp ground cumin
• 1/2 tsp smoked paprika
• 1/2 tsp pepper
• 1/2 tsp chili powder
• 1/4 tsp cayenne pepper
• 3/4 cup cooked quinoa
• 1/2 cup bread crumbs
• 2 Tbsp olive oil
• 6 burger buns, toasted
• 1 ripe avocado, thinly sliced
• 1 1/2 cups arugula
• 1/3 cup barbecue sauce