Remove the sausage casings, and crumble the meat into a large bowl. Pour 1/2 cup of the wine over the meat and mix this in with your fingers, breaking up any big meat clumps, so the sausage is evenly moistened.
Pour the olive oil into the big skillet and set it over medium heat. Stir in the onions and cook until they begin to soften, about 5 minutes. Scatter the sliced garlic in the pan and season with the salt and peperoncino. When everything is sizzling, crumble in the sausage and stir with the onions. Pour in the remaining 1/2 cup wine, raise the heat a bit and cook, stirring, as the wine cooks away and the sausage becomes all browned, about 10 minutes. Add in the diced zucchini and stir to incorporate. Pour in the tomatoes and a cup of water (which you’ve used to slosh and rinse the tomato cans and bowl). Submerge the basil branch in the liquid, cover the skillet and bring to a boil. Set the cover ajar, adjust the heat to keep the sauce bubbling steadily and cook for an hour or more, until the sauce has developed good flavor and reduced to the consistency you like for dressing pasta. Remove and discard basil branch. You can use some of the sauce right away—you’ll need half of it to dress the rigatoni—or let it cool, then refrigerate or freeze for later use.