01 - Bring a large pot of salted water to a rolling boil. Add fusilli or rotini pasta and cook according to package directions until al dente. Drain well and rinse under cold running water to halt cooking. Set aside to cool completely.
02 - Place corn ears on a preheated hot grill or grill pan. Cook for 8 to 10 minutes, rotating every couple of minutes, until kernels are lightly charred and blistered. Let cool until handleable, then stand each ear upright and slice kernels from the cob. If using frozen corn, toast in a dry skillet over high heat until golden and slightly charred.
03 - In a large mixing bowl, combine mayonnaise, sour cream, lime zest, lime juice, chili powder, smoked paprika, cayenne pepper if using, sea salt, and black pepper. Whisk until smooth and fully blended.
04 - Add the cooled pasta, grilled corn kernels, diced red bell pepper, red onion, green onions, and chopped cilantro to the dressing. Toss thoroughly until every element is evenly coated.
05 - Gently fold crumbled cotija cheese into the salad. Add finely diced jalapeño and diced avocado at this stage if desired, folding carefully to avoid mashing.
06 - Cover and refrigerate for at least 30 minutes so the flavors meld together. Taste before serving and adjust salt and seasoning as needed.