Cook the pasta in a large pot of salted boiling water until al dente, then drain and rinse under cold water to cool.
Meanwhile, heat a skillet over medium‑high heat. Add the corn kernels and cook until lightly charred and slightly blistered, stirring occasionally.
In a large bowl, whisk together the mayonnaise, sour cream (or crema), lime juice, chili powder, cayenne (if using), salt, and pepper.
Add the cooled pasta to the dressing and toss gently to coat.
Fold in the charred corn, cotija cheese, cilantro, red onion, and jalapeño and check seasoning and add more salt, pepper, or lime juice if needed.
Garnish with lime zest and an extra sprinkle of cotija before serving.
