Chipotle Corn Salad

5 ears of corn
1/2 medium Vidalia or Walla Walla onion, thickly sliced crosswise
1 tablespoon extra-virgin olive oil
1/4 cup plus 2 tablespoons sour cream
2 tablespoons fresh lime juice
2 chipotle chiles in adobo sauce, seeded and finely chopped
1 scallion, thinly sliced
Salt and freshly ground pepper

Light a grill or preheat a grill pan. Brush the corn and onion slices with the olive oil and grill over moderately high heat until charred in spots but still slightly crisp, about 7 minutes. Let cool slightly, then cut the kernels from the cobs and coarsely chop the onion.

In a medium bowl, mix the sour cream with the lime juice, chopped chipotle chiles and sliced scallion and stir in the charred corn and onions. Season the corn salad with salt and pepper and serve immediately.