Put the corn, walnuts, chiles, scallions, and mint in a bowl and toss to mix. Squeeze over the lime juice and season generously with salt and black pepper. Taste and adjust the seasoning so that the corn is lively with flavor. Add ¼ cup olive oil and toss. Taste and adjust with more oil, lime, salt, or black pepper.
Serve the corn salad in a bowl and top with the shredded pecorino.