Pour 2 tablespoons of the olive oil into a big skillet or sauté pan and set over medium-high heat. Lay in all the sausages and cook for 5 minutes or more, rolling them over occasionally, until nicely browned on all sides.
Pour in wine and boil until it is reduced by half. Remove sausages to a platter and pour the wine over them.
Add the remaining 2 tablespoons olive oil and garlic cloves to the skillet and cook over medium heat for a minute or so, until they’re sizzling. Drop the peperoncino in a hot spot for a few seconds, then scatter the squashed olives in the pan; toss and cook for a couple of minutes.
Add fennel chunks to the skillet and stir in with the garlic and olives. Season the vegetables with salt, cover and cook over medium-high heat for 20 minutes, tossing and stirring now and then, until the fennel softens, shrinks and begins to color. (Add a bit of water if the fennel remains hard and resistant to the bite.)
When the fennel is cooked through, return the sausages and wine to the skillet. Turn the meat and vegetables together and cook uncovered for 5 minutes, until everything is deeply caramelized and glazed.
Adjust the seasoning to taste; keep tumbling the sausages and fennel. Serve piping hot. Makes 6 servings.
*Brands may vary by region; substitute a similar product.