Cook the Ground Beef: In a large skillet over medium heat, cook the ground beef until browned, breaking it apart with a spatula. Drain any excess fat. Add the taco seasoning and water, and stir until the beef is well coated. Let simmer for 2-3 minutes. Remove from heat and set aside to cool slightly.
Prepare the Salad: In a large salad bowl, combine the chopped lettuce, halved cherry tomatoes, shredded cheese, diced red onion, black beans, and corn. Toss until evenly mixed.
Add the Beef and Doritos: Add the seasoned ground beef to the salad mixture and toss to combine. Just before serving, add the crushed Doritos to maintain their crunch.
Dress the Salad: Pour the Catalina dressing (or ranch dressing) over the salad and gently toss until all ingredients are well coated. If desired, add a squeeze of lime juice for extra tang.
Serve: Serve the Dorito Taco Salad immediately, while the Doritos are still crispy. Enjoy!