1. In a large pot of boiling salted water, cook the broccoli rabe until tender, about 2 minutes. Drain, then rinse in cold water and drain again thoroughly. Cut into 2-inch pieces and set aside.
2. Heat 1 tablespoon of the extra-virgin olive oil in a large heavy skillet. Add the sausage and cook over moderately high heat, turning occasionally, until browned and cooked through, about 10 minutes. Transfer the sausage to a plate and let cool slightly. Slice the sausage into 1/2-inch-thick rounds.
3. Pour off all but 2 tablespoons of the fat from the skillet. Add the onion and garlic and cook over moderately low heat, stirring occasionally, until the onion is translucent, about 5 minutes. Stir in the wine and bring to a simmer. Stir in the sausage slices, tomatoes, stock, thyme and 1 1/4 teaspoons of the salt. Bring to a simmer and cook for 20 minutes. Add the broccoli rabe, parsley and pepper and return to a simmer.
4. Meanwhile, in a medium saucepan, combine the water and the remaining 1 1/4 teaspoons of salt and bring to a boil. Whisk in the cornmeal in a slow steady stream, then whisk in the remaining 3 tablespoons of oil. Reduce the heat and simmer, stirring frequently with a wooden spoon, until the polenta is thickened, about 20 minutes.
5. Spoon the polenta onto dinner plates and top with the sausage and broccoli rabe ragout.
Wine Recommendation: This dish wants a red wine without a high level of tannins, which could combine with the broccoli rabe to create an unpleasant bitterness. One excellent choice: an Italian Barbera with minimal tannin, such as the 1995 Michele Chiarlo Barbera d'Asti.