01 - Bring a large pot of salted water to a boil. Cook fusilli or rotini according to package directions until al dente. Drain 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, turning occasionally, until kernels are lightly charred and smoky. Let cool, then stand each ear upright and slice kernels from the cob. If using frozen corn, sauté in a dry skillet over high heat until lightly blackened.
03 - In a large mixing bowl, whisk together mayonnaise, sour cream, lime zest, lime juice, chili powder, smoked paprika, cayenne pepper (if using), sea salt, and black pepper until smooth and well combined.
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 component is evenly coated.
05 - Gently fold in crumbled cotija cheese. If desired, add finely diced jalapeño and diced avocado at this stage.
06 - Cover and refrigerate for at least 30 minutes to allow the flavors to develop. Taste before serving and adjust salt, pepper, or lime juice as needed.