Preheat your grill to medium-high heat. Gather your corn and prepare a clean surface for grilling.
Place the corn on the grill, turning every 2-3 minutes. Grill until kernels are charred in spots and slightly softened, about 10-12 minutes, visually showing deep grill marks and lightly blistered kernels.
Meanwhile, whisk together mayonnaise, lime juice, chili powder, and a pinch of salt and pepper in a small bowl until well combined.
4 ears corn on the cob
Remove the corn from the grill and brush generously with the prepared sauce using a basting brush. Ensure kernels are coated evenly and visibly creamy, with some charred spots still showing.
4 ears corn on the cob
Sprinkle crumbled cotija cheese evenly over the coated corn while still warm. The cheese should begin to melt slightly into the sauce, creating a thick, flavorful coating.
4 ears corn on the cob
Serve the corn hot, garnished with additional chili powder, a squeeze of lime if desired, and fresh herbs for presentation. The final appearance is a vibrant, slightly charred ear of corn with a creamy, cheesy coating and smoky aroma.