1. In a large pot of boiling, salted water, cook the broccoli rabe until tender, about 2 minutes. Drain. Rinse with cold water and drain thoroughly. Cut into 2-inch lengths.
2. In a large frying pan, heat 1 tablespoon of the oil over moderately high heat. Add the sausage and cook, turning, until browned, about 10 minutes. Remove. When cool enough to handle, cut into slices.
3. Pour off all but 2 tablespoons of the fat from the pan. Reduce the heat to moderately low. Add the onion and garlic and cook, stirring occasionally, until translucent, about 5 minutes. Add the wine; bring to a simmer. Add the sausage, tomatoes, broth, thyme, and 1 1/4 teaspoons of the salt. Bring to a simmer. Cook, uncovered, for 15 minutes. Add the broccoli rabe, parsley, and pepper to the sauce; bring to a simmer.
4. Meanwhile, in a medium saucepan, bring the water and the remaining 1 1/4 teaspoons salt to a boil. Add the cornmeal in a slow stream, whisking. Whisk in the remaining 3 tablespoons oil. Reduce the heat and simmer, stirring frequently with a wooden spoon, until very thick, about 20 minutes. Serve with the sauce.
Wine Recommendation: This rustic dish wants a red wine, but the broccoli rabe's bite will combine with tannin to create an unpleasant bitterness. Opt for an Italian barbera; it has minimal tannin.