Preheat broiler for 10 minutes and place rack 5 inches from heat source. Prep all ingredients before getting started, as you will need to work quickly once chiles are ready for stuffing.
In a large bowl, mix yogurt, lime juice, and 1/2 tablespoon cilantro until combined. Set aside in the refrigerator until ready to use.
Place chiles on a baking sheet and broil for about 3–5 minutes on each side, until charred but still firm.
Remove from oven and immediately place in a bowl; cover to steam and let sit for about 15 minutes. Remove skin and split each chile down the center, creating a seam (don’t cut all the way through). Remove seeds, and keep the stem intact. Place chiles in a small casserole dish.
While chiles are steaming, heat oil in large skillet over medium-high heat and add diced onion. Once softened, add ground beef and spices. Once the meat is cooked through, add corn and tomatoes. Stir to combine, and remove from heat.
Using a spoon, stuff the meat mixture into the prepared chiles. Top with cheese and broil for a few minutes, until the cheese starts to bubble and brown.
Drizzle the yogurt-lime mixture over chiles, top with the remaining fresh cilantro, and serve.
Notes
Leftover stuffed chiles will last up to 3 days in the refrigerator in a sealed container. Warm them in the oven to serve again.