How to Make It
Roast the poblanos directly over a gas flame or under a broiler, turning, until charred all over. Transfer to a bowl, cover with plastic wrap and let stand for 10 minutes. Peel, core and seed the chiles, then cut them into thin strips.
In a medium saucepan, heat 2 tablespoons of the olive oil until shimmering. Add the onion and cook over moderate heat, stirring, until softened, about 5 minutes. Add the corn and poblano strips and cook until the corn is tender, about 2 minutes. Stir in the sour cream and season with salt and pepper. Keep the corn warm over very low heat.
Light a grill or preheat a grill pan. Rub the steaks with the remaining 2 tablespoons of oil; season with salt and pepper. Grill over high heat, turning once, until lightly charred, about 6 minutes. Let the steaks rest for 5 minutes, then thinly slice across the grain. Serve with the corn and poblanos.