Inspired by the Alsatian classic choucroute garni, this comforting, one-pot meal takes a shortcut with bagged shredded cabbage. Serve topped with additional brown mustard, if you like.
Heat 1 teaspoon oil in a large skillet over medium-high heat. Add sausage and cook, turning often, until lightly browned, about 3 minutes. Transfer the sausage to a cutting board and slice into 1/2-inch pieces. (The sausage will not be thoroughly cooked, but it will continue cooking later.)
Add the remaining 1 teaspoon oil to the pan and heat over medium heat. Add potatoes and cook, stirring occasionally, for 3 minutes. Add cabbage, sliced fennel, onion, garlic powder, fennel seed and pepper. Cook, stirring often, until the cabbage has wilted slightly, about 3 minutes more.
Add broth, vinegar and mustard. Stir to incorporate the mustard; bring to a simmer. Place the sausage on top of the cabbage mixture; cover, reduce heat to medium-low and cook until the sausage is cooked through and the vegetables are tender, 7 to 10 minutes. Stir in chopped fennel fronds and serve.
Tips for Two: Refrigerate leftover cabbage for up to 1 week. Add to salads or soup; Vinegary Coleslaw or Warm Apple-Cabbage Slaw.