Fire roast the corn and poblano over an open flame or under a broiler. For the corn you just want to add some color, not fully charred. On the other hand, for the poblano you want to get them completely blackened. Using metal tongs turn them frequently - be careful the tongs will get hot. You'll then transfer them to a metal bowl, cover with plastic wrap, and rest 5 minutes before rinsing under cold running water to remove the charred skins.
Cut the corn kernels off the cobs. Remove the stems and seeds of the poblanos and dice. In a small bowl combine corn and diced poblano peppers to remaining ingredients. Adjust seasoning to taste.