Fish Corn and Chorizo Grill Packets

Name: Fish, Corn, and Chorizo Grill Packets
Ingredients: 1 tablespoon olive oil, plus more for the grill; 3 cups corn kernels (from 3 to 4 ears); 4 ounces cured chorizo, thinly sliced; kosher salt and black pepper; 4 6-ounce skinless black bass, tilapia, or Pacific halibut fillets; 8 sprigs fresh oregano, plus leaves for serving; lime wedges, for serving (optional)