Make the dressing first. In a medium bowl, whisk the mayonnaise, sour cream, ranch seasoning, taco seasoning, lime juice and milk until thoroughly combined. Add more milk if you want a thinner consistency, but the dressing needs to be thick enough to coat the salad. Cover and chill in the refrigerator for at least one hour.
For the salad: In a large bowl, add the bell pepper, tomatoes, green onions, cilantro, corn, black beans and garbanzo beans. Stir to combine. Now add the romaine lettuce and stir the salad to evenly combine all of the ingredients.
At this point, you can put the salad mixture into individual bowls or continue in the large salad bowl. Pour the desired amount of dressing over the salad and gently stir to coat the salad with the dressing. Mix in the crushed tortilla chip. Serve immediately.
Enjoy!