Boil 2 quarts water. Add pasta, cook until barely tender 9-11 minutes. Drain and rinse with cold water. In large mixing bowl, mix pasta, beans, corn, tomato, cilantro, onions, lime and lime juice. Toss to combine. Add seasonings, including salt and pepper to taste.
In small bowl, mash avocado with 1 tablespoon lime juice, sour cream and Tabasco. Add salt and pepper.