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