Char 1 large poblano pepper over the flame of a gas burner on high heat (or char under the broiler). Transfer to a bowl, cover with plastic wrap and let cool. Remove the skin, stem and seeds; chop the poblano. Melt 2 tablespoons butter in a skillet over medium heat. Add the poblano, 2 cups fire-roasted corn and 1 teaspoon ground cumin; season with salt and pepper. Cook, tossing, until hot, 5 to 6 minutes.