1. In a medium bowl, mash avocado with a fork. Add cilantro, garlic, yogurt, lime juice, olive oil & vinegar. Mix well, cover & refrigerate until ready to serve.
2. Tear lettuce leaves into bite-sized piece & place place in a large bowl.
3. Add beans, peppers, tomatoes, corn & onions. Toss to combine.
4. To serve, drizzle dressing over salad.