Pasta: prepare pasta according to package directions. Drain. Rinse with cold water; set aside.
Beef: In a large skillet, brown beef, drain excess grease. Stir in taco seasoning and water, bring to a boil, reduce heat and simmer for 3-4 minutes or until liquid has absorbed. Set aside until meat is cooled.
Salad: Toss together cooled meat, pasta, tomatoes, onion, cheese and beans. Mix dressing and mayo together and stir into pasta mixture. Enjoy!