Bring 3 L / 3 quarts of water and 1 tbsp coarse salt to a boil in a 5-quart / 4.7 L pot. While it heats, trim 2 to 3 cm off the stem ends of the greens and cut off any stalk thicker than a pencil. Blanch the greens for 3 minutes, drain, and rinse under cold water. Squeeze them hard in a clean towel and chop into 5 cm / 2-inch pieces. Don't skip this step with thick-stemmed bunches, or the finished dish stays sharply bitter.

Slice the sausage links into 2.5 cm / 1-inch rounds. Heat 2 tbsp olive oil in a 30 cm / 12-inch deep skillet over medium heat. Add the sausage in a single layer and cook for 7 to 8 minutes, turning once, until deeply browned on both cut sides and cooked through to 160 F / 71 C.

Spoon off all but about 2 tbsp of fat if the pan holds more. Add the garlic and red pepper flakes and stir for 30 to 45 seconds until the garlic turns pale gold. Pour in the wine, scrape up the browned bits, and simmer for 2 minutes until reduced by about half.

Add the greens and toss with tongs to coat in the pan juices. Cook for 6 to 8 minutes over medium heat, stirring every minute or so, until the stems are tender and the liquid has nearly evaporated. Taste, then season with the fine sea salt and drizzle with the remaining 1 tbsp olive oil. Serve straight from the skillet with lemon wedges.