How to Make It
Preheat the oven to 350° and place a 9- or 10-inch cast-iron skillet in it to heat. Using a box grater, coarsely grate the corn into a bowl, reserving all of the solids and juices. Add the oil to the hot skillet and swirl to coat. Spread the corn and juices in the skillet and bake for 45 minutes, until browned and crusty on the bottom. Scrape the corn into a saucepan and stir in the butter and lime juice. Season with salt and cayenne; keep warm.
In a large cast-iron skillet, heat the oil. Add the andouille and cook over moderate heat until browned, 2 minutes; transfer to a plate. Set the skillet over high heat and when the oil is almost smoking, add the collards and cook, undisturbed, until slightly charred, 1 minute. Stir and cook for 30 seconds longer. Add the andouille, shallot and chile and cook over moderate heat, stirring, until the shallot is softened, 1 minute. Add the radishes and scallion and cook, stirring, for 30 seconds. Scrape the collards into a bowl and stir in the lime juice. Season with salt, cover and keep warm.
Reduce the oven temperature to 325°. Heat a grill pan. Rub the grouper with oil and season with salt and cayenne. Grill over high heat, skinned side up, until lightly charred, 2 to 3 minutes. Turn and transfer to a large baking sheet. Top each fillet with 1/2 tablespoon of butter and bake for about 3 minutes, until cooked through.
Spoon the corn into small bowls. Spoon the collards onto plates and top with the grouper fillets and any pan juices. Serve right away with the corn.