Saute the corn with the salt and pepper, about 5 minutes. Transfer to a large mixing bowl and set aside to cool.
Cut the avocados, bell pepper and roasted poblanos into 1/4 inch dice. Add to the sauted corn along with the scallions, vinegar and remaining 1/4 cup olive oil. Mix well and let sit 20 to 30 minutes to blend the flavors.
Serve at room temperature. Corn relish can be stored, tightly covered, in the refrigerator up to 1 day. To make 2 to 3 days in advance, mix all the ingredients except the avocado and store in the refrigerator. Add the avocado shortly before serving.
Fresh chiles and bell peppers can be roasted over a gas flame or on a tray under the broiler. Keep turning so the skin is evenly charred, without burning and drying out the flesh. Transfer the charred peppers to a plastic bag, tie the top closed and let steam until cool to the touch, about 15 minutes. (If you are rushed, you can place the bag in a bowl of iced water to speed things up.) The best way to peel is just to pull off the charred skin by hand and then dip the peppers briefly in water to remove any blackened bits. Do not peel the pepper under running water since that will wash away flavorful juices. Once peeled, cut away stems, seeds and veins.
c.1997, M.S. Milliken & S. Feniger, all rights reserved