Place Japgokbap or other cooked grains in a medium bowl, toss with sesame oil, and set aside.
Heat a grill to high. Rub the corn cobs with a small amount of oil and grill over direct heat until just cooked. Cut the corn off of the cobs and reserve.
In a medium cast-iron skillet set over medium-high heat, add 2 tbsp. oil. Add onion, red bell pepper, and garlic, and sauté until the vegetables begin to soften, 3–5 minutes. Add grilled corn kernels, Korean chili flakes, and soy sauce, and sauté another minute. Remove skillet from the heat.
Using a spoon, layer the cooked grains over the corn mixture.
In a medium bowl, whisk together mayonnaise, sour cream, curry powder, and 2 tbsp. water. Pour creamy mixture on top of the corn and grains in the skillet.
Top with shredded mozzarella, pepper jack, and scallions. Set the skillet on the grill and close the grill lid, or place the skillet in a preheated 425°F oven. Bake 20–30 minutes, until the cheese is melted and bubbly and lightly browned. Serve immediately, but take care not to burn your mouth on the hot cheese!