Cut each sausage link into 4 pieces. Heat 1 tablespoon of the oil in a large skillet over medium heat. Add the sausage and cook until brown all over, about 4 minutes. Remove with a slotted spoon to a plate.
Add the remaining tablespoon oil to the skillet. When hot, add the peppers, onion and zucchini and season with salt. Cook, tossing, until the vegetables just begin to soften, about 4 minutes. Add the wine and reduce until syrupy, about 2 minutes. Add the tomatoes, red pepper flakes and 1/2 cup water. Bring to a simmer and cook until slightly thickened and the flavors have melded, about 10 minutes.
Return the sausage to the skillet, stir in the spinach and simmer until the sausage is heated through and the spinach is wilted, about 2 minutes.
Meanwhile, put 4 cups water and 1 teaspoon salt in a medium saucepan and bring to a simmer over medium heat. Whisk in the polenta. Simmer until thickened, about 5 minutes. Remove from the heat and stir in the grated Pecorino Romano and butter. Season with salt, if needed.
To serve, chop the basil leaves and stir into the sauce. Spoon the hot polenta into 4 shallow bowls. Top each with some of the tomato mixture. Use a vegetable peeler to shave more cheese over the top and garnish each serving with a basil sprig.
Party Version: Make the polenta following the directions above. Spread the finished polenta onto 2 parchment-lined baking sheets in a thin even layer and refrigerate until set, about 30 minutes.
Cut the polenta into squares (about 1 1/2 inches) and transfer to 2 parchment-lined baking sheets (or re-line the original baking sheets). Bake at 325 degrees F until crisp, about 35 minutes. (The polenta squares will continue to crisp up as they cool.)
Cut the sausage into thin rounds, then cook and remove following the directions above.
Chop the bell peppers, onion and zucchini a little more finely than called for above, then follow the directions for making the tomato sauce. Add the browned sausage (but not the spinach) to the skillet and simmer until heated through, about 2 minutes.
To serve, lay a spinach leaf on each polenta crisp. Top with a dollop of the tomato mixture and a sausage round. Shave a bit of the Pecorino Roman onto each and top with a basil leaf.