Cook the rotini pasta according to package instructions until al dente. Drain and rinse under cold water to cool.
In a large mixing bowl, combine the cooked pasta, cherry tomatoes, corn, black beans, red onion, and cilantro.
In a separate small bowl, whisk together the lime juice, olive oil, garlic powder, cumin, salt, and pepper until well combined.
Pour the dressing over the pasta salad and toss gently to coat all ingredients evenly.
If using, gently fold in the diced avocado just before serving.
Chill the pasta salad in the refrigerator for at least 30 minutes to allow the flavors to meld. Serve cold or at room temperature.