Heat the oil in a large wok or nonstick skillet over high heat until shim-mering. Add the corn kernels, season to taste with salt, toss once or twice, and cook, without stirring, until charred on the first side, about 2 minutes. Toss the corn, stir, and repeat until charred on a second side, about 2 minutes longer. Continue tossing and charring until the corn is well charred all over, about 10 minutes total. Transfer to a large bowl.
Add the mayonnaise, cheese, scallions, cilantro, jalapeño, garlic, lime juice, and chili powder to taste and toss to combine. Taste and adjust the seasoning with salt and more chili powder if desired. Serve hot or at room temperature.