How to Make It
Preheat a gas grill to medium-high (400°F to 450°F) on 1 side. Place poblano chiles and corn on oiled grates over lit side of grill. Cover grill. Grill poblanos, turning once, until skins are charred, about 5 minutes per side. Grill corn, turning occasionally, until charred, about 5 minutes per side. Remove poblanos and corn from grill.
Transfer poblanos to a heavy-duty ziplock plastic bag. Seal and let stand 10 minutes.
Meanwhile, let corn cool 5 minutes. Cut kernels from cobs, discarding cobs. Set aside kernels.
Remove poblanos from plastic bag. Remove and discard skins, keeping stems intact. Working with 1 at a time, make a lengthwise slit down side of poblano, starting at the stem and being careful to not cut through the other side of the pepper. Carefully remove and discard seeds and membrane. Set aside poblanos.
Heat butter in a large skillet over medium-high until melted and foamy. Add peas. Cook, stirring often, until hot, about 2 minutes. Stir in reserved corn kernels, garlic, salt, cumin, and black pepper. Cook, stirring often, 2 minutes. Stir in cilantro and oregano. Remove from heat; stir in cheese.
Spoon pea mixture evenly into poblanos, pulling sides of each chile around the filling to enclose. Transfer poblanos to a baking sheet lightly coated with cooking spray. Place on unlit side of grill. Grill, covered, until cheese is melted and bubbling, about 5 minutes. Serve immediately with pico de gallo on the side for topping.