Preheat the oven to 400°F.
Toss the potatoes in oil, garlic powder, salt and pepper and place on a foil-lined baking sheet, roast for 20 minutes then turn the potatoes. Add the sausage to the baking sheet.
Cook the sausage on both sides until an internal temperature of 160°F is reached. Remove the sausage from the heat and set aside.
Add the broth, vinegar, and cabbage to a pot over medium heat. Cover with a lid and bring to a simmer for 15-20 minutes until the cabbage starts to wilt and becomes tender. Season with salt and pepper.
Once the cabbage is tender, remove the lid and add in the butter. Continue to simmer for about 5 minutes. Taste and adjust the seasoning with salt. Drain the majority of the liquid before serving.
Slice the sausage and serve with the cabbage, potatoes, and crusty bread. Serve with mustard if desired.