While your pan heats, prepare all your ingredients so you can work quickly once cooking begins. Crumble the cotija cheese, thinly slice the scallions, chop the cilantro, seed and mince the jalapeño, and mince the garlic cloves. Having everything ready means you won't scramble during the cooking process.
Heat the vegetable oil in a large skillet over high heat until it shimmers, then add the corn and kosher salt. Let the corn sit undisturbed for 2 minutes to develop a golden char—this creates those delicious caramelized bits that give the salad its signature depth. Stir and continue cooking for another 2 minutes, then stir occasionally for about 6 more minutes until the corn is deeply charred and tender. I find that not moving the corn at first is crucial; it allows the kernels to make direct contact with the hot pan and build real color and flavor.
Transfer the charred corn from Step 2 to a large serving bowl. In a small bowl, whisk together the mayonnaise, fresh lime juice, chili powder, smoked paprika, and ground cumin to create the creamy, spiced dressing. I like to make this dressing separate first so the spices can fully incorporate into the mayo, creating a more cohesive sauce rather than having grains of spice settling at the bottom.
Pour the spiced dressing from Step 3 over the charred corn, then add the crumbled cotija cheese, sliced scallions, chopped cilantro, minced jalapeño, and minced garlic from Step 1. Gently fold everything together until the corn is evenly coated. Taste the salad and adjust the seasoning with additional kosher salt and chili powder as needed—the heat and saltiness should balance with the creaminess and brightness of the lime.