1 medium head green cabbage (about 2 pounds)
1 large yellow onion, peeled and thinly sliced
1 large carrot, cleaned or peeled if necessary and cut into ¼-inch rounds
¼ cup olive oil
¼ cup chicken broth or water
Kosher salt and freshly ground pepper
1. Preheat the oven to 325 degrees. Lightly oil a large gratin or baking dish.
2. Peel and discard any torn, tough or discolored outer leaves from the cabbage. Core the cabbage, cut it into eight wedges and arrange them, in a single layer or overlapping slightly, in the dish. Scatter the onion and carrot over the cabbage, drizzle with the oil and broth and season generously with salt and pepper and pepper flakes.
3. Cover the dish tightly with foil and place it in the oven. Cook until quite tender, about two hours, turning after one hour. Add water by tablespoons if the dish seems to be drying out.
4. When the cabbage is tender, remove the foil, increase the temperature to 400 °F, and continue to cook until the vegetables begin to brown. Serve warm or at room temperature, sprinkle with sea salt.