For the Dressing:
1 ripe avocado, peeled, pit removed
1/2 lime, juiced
1 small clove garlic, chopped
pinch cayenne pepper, or more to taste
For the Salad:
6 cups romaine lettuce, chopped
4 cups mixed baby greens
1 cup cooked black beans
1 cup frozen, thawed corn kernels
1 medium tomato, chopped
1/4 cup chopped red onion