Cook the rotini pasta according to package directions until al dente. Drain and rinse under cold water to cool the pasta completely, then set aside.

In a large skillet over medium heat, cook the ground beef until browned and fully cooked, breaking it apart with a spoon as it cooks. Drain excess grease if needed.

Sprinkle the taco seasoning over the cooked beef and add a few tablespoons of water according to the seasoning packet directions. Stir well and simmer for a couple of minutes until the beef becomes flavorful and slightly saucy. Remove from heat and allow it to cool slightly.

In a large mixing bowl, combine the cooked pasta, taco-seasoned beef, black beans, corn, diced red bell pepper, cherry tomatoes, shredded cheddar cheese, and sliced green onions. Toss gently to distribute all the ingredients evenly.

In a separate bowl, whisk together the sour cream, mayonnaise, taco sauce, lime juice, garlic powder, salt, and black pepper until smooth and creamy.

Pour the dressing over the pasta mixture and toss thoroughly until everything is evenly coated in the creamy taco dressing.

Cover the bowl and refrigerate the pasta salad for at least 30 minutes before serving so the flavors can blend together.

Before serving, give the salad a gentle stir and garnish with extra green onions, cheese, or crushed tortilla chips if desired. Serve chilled.