Step 1: If using fresh corn, husk and boil or grill for 5-7 minutes until tender-crisp. Let cool slightly, then cut the kernels off the cob. If using frozen corn, thaw completely and pat dry with paper towels to remove any excess moisture.
Step 2: In a large mixing bowl, combine the prepared corn, diced red bell pepper, diced red onion, and minced jalapeño (if using). Add the shredded sharp cheddar cheese. Gently toss to distribute the ingredients evenly.
Step 3: In a separate medium bowl, whisk together the mayonnaise, sour cream (or Greek yogurt), fresh lime juice, chili powder, ground cumin, salt, and black pepper until smooth. Taste the dressing and adjust seasonings as needed.
Step 4: Pour the whisked dressing over the corn and vegetable mixture. Stir gently with a spatula until all the ingredients are well coated. Cover the bowl and refrigerate for at least 30 minutes, or up to 2 hours, to allow the flavors to meld.
Step 5: Just before serving, add the Frito corn chips to the salad. Gently fold them in until they are evenly distributed. Serve immediately to ensure maximum crispness. If desired, you can serve extra Fritos on the side.