Broccoli rabe (also raab or rapini) is leafy green and related to cabbages and turnips. Popular in Italian cooking, it has mildly bitter flavor and crunchy texture that contrasts with the creaminess of polenta in this recipe.
Prepare polenta according to package directions. Cover and keep warm.
In a large skillet cook onion in hot oil over medium heat for 4 to 5 minutes or until tender, stirring occasionally. Add garlic; cook and stir for 30 seconds. Add broccoli rabe. Cook, covered, about 3 minutes or just until tender. (If using broccoli florets, cook and stir for 3 to 4 minutes or until crisp-tender.) Stir in roasted red peppers.
In a small bowl gradually stir broth into cornstarch; add to vegetable mixture. Cook and stir over medium heat until thickened and bubbly. Cook and stir for 2 minutes more.
To serve, spoon vegetable mixture over polenta. Sprinkle with toasted nuts.