Five-Ingredient Veggie Burger - Forks Over Knives

Ingredients

• 2 cups no-salt-added canned black beans, drained and liquid reserved
• 1 medium onion, quartered
• ½ cup quick-cooking rolled oats (see gluten-free tip, recipe intro)
• 1 Tbsp. lime juice
• 2 tsp. chili powder (see gluten-free tip, recipe intro)
• Sea salt and freshly ground black pepper, to taste
• Avocado oil cooking spray (optional, <a href="#h-tips">learn more</a>)
• 4 100% whole grain hamburger buns, split and toasted (see gluten-free tip, recipe intro)
• 4 leaves leaf lettuce
• 1 tomato, sliced
• 2 red onion slices, separated
• Condiments of your choosing (see headnote)