How to Make It
Preheat the oven to 425°. In a large, deep ovenproof skillet, heat the 2 tablespoons of oil. Add the radishes (not the greens) and turnips and season with salt and pepper. Cook over moderately high heat, tossing occasionally, until browned in spots, 2 minutes. Transfer the skillet to the oven and roast for about 10 minutes, until tender.
Meanwhile, put the flour, eggs and cereal in 3 separate shallow bowls. Season the hake with salt and pepper; dust with the flour. Dip in the egg, then in the Cream of Wheat, pressing to help the cereal adhere.
In a large nonstick ovenproof skillet, heat 1/4 inch of oil until shimmering. Add the hake and cook over moderately high heat, turning once, until browned and crisp on both sides, about 6 minutes total. Transfer the skillet to the oven and bake for 5 to 7 minutes, until the fish is cooked through.
Put the skillet with the radishes and turnips over moderate heat. Add the butter, spinach and radish greens and cook until just wilted. Stir in the mustard and lemon juice and season with salt and pepper. Transfer to plates with the fish.