Sweet Italian sausage and tender sauteed cabbage transform spaghetti into a sophisticated meal that's suited to the season's cool weather.
In a large pot of boiling salted water, cook pasta until al dente. Reserve 1 cup pasta water; drain pasta, and return to pot. Set aside.
While pasta is cooking, heat oil in a large nonstick skillet over medium-high. Add sausage; cook, breaking up with a wooden spoon, until browned and cooked through, 4 to 6 minutes. With a slotted spoon, transfer sausage to a plate; set aside (reserve skillet with rendered fat).
To skillet, add onion, 2 tablespoons water, and as much cabbage as will fit; season with salt and pepper. Cover; cook until tender, tossing occasionally and adding more cabbage as space becomes available, 6 to 10 minutes.
To pasta, add cabbage mixture and sausage. Toss with enough pasta water to create a sauce. Season with salt and pepper, and stir in vinegar.