1. Preheat your grill to medium-high heat. Brush the corn with vegetable oil and season with a pinch of salt.
2. Grill the corn, turning occasionally, until cooked through and charred in spots, about 10 to 12 minutes.
3. While the corn is grilling, mix the mayonnaise, sour cream, garlic powder, smoked paprika, and cumin in a bowl until well combined.
4. Once the corn is grilled, spread the mayo mixture over each ear of corn. Be generous and ensure all sides are covered.
5. Sprinkle the crumbled cotija cheese over the corn, turning it so the cheese covers the mayo layer completely.
6. Finish by squeezing lime juice over each ear and garnishing with the chopped cilantro.
7. Serve immediately with extra lime wedges on the side.