Serve this salsa as a dip for chips or as a relish to accompany grilled pork tenderloin or chicken.
Heat a large heavy skillet, preferably cast-iron, over medium-high heat. Roast corn (still on the cob), turning frequently, until the kernels are darkened on all sides, about 8 minutes.
When the corn is cool enough to handle, cut the kernels off the cobs and transfer to a small bowl. Stir in salsa, lime juice, cilantro and cumin.