For the soup, heat a Dutch oven or deep pot over medium heat with EVOO and the onions and cook to golden in color and lightly caramelized. Add garlic and stir a minute or 2. Add the cabbage and season with salt, pepper of choice and nutmeg. Wilt the cabbage 7 to 8 minutes while stirring, then add vinegar. Cover the pot and turn heat to low. Cook 1 ½ hours, stirring occasionally.
Add stock and the rice to the smothered cabbage and simmer about 20 minutes until the rice is al dente, then stir in butter and cheese and serve.
For the sausages, preheat oven to 400°F.
Combine fennel and onion on parchment-lined sheet pan. Season with salt and pepper and drizzle with olive oil. Place sausage/protein on top of onions and fennel and transfer to oven. Roast until sausage/protein is fully cooked, about 20 minutes. Garnish with fennel fronds.
For the gremolata, pile all ingredients on a cutting board and run your knife through them until finely chopped and combined. Sprinkle on top of soup.
