Mexican Street Corn Salad (Elote Salad)

If using fresh corn, remove the husks and, using a sharp knife, slice the corn kernels from the cobs by placing each ear upright in a bowl. Discard cobs. If using frozen corn, thaw according to package directions and pat dry.
Heat a large cast-iron skillet over medium-high heat with the oil until very hot. Add the corn and salt in a single layer. Let the corn sit and cook for several minutes until brown on one side (careful, the kernels sometimes jump!). Stir, and continue to cook several more minutes until the corn kernels have a nice brown char. Spoon the corn into a large bowl.
TIP: You may want to char the corn in a couple of batches. You can also cook the corn under the broiler.
In a small mixing bowl, whisk together the mayonnaise, chili powder, the juice of one lime, garlic, and shallot. Add to the corn and stir to combine.
Crumble the cotija cheese all over the salad, reserving a bit for garnish. Add the tomatoes and cilantro. Stir to combine.
Serve, garnishing with the reserved cotija and lime wedges from the second lime.