Heat oven to 450° F.
Toss the sweet potatoes and cabbage with the olive oil and ½ teaspoon each salt and pepper on a rimmed baking sheet.
Combine the fennel, caraway, 1 teaspoon salt, and ½ teaspoon pepper in a small bowl. Coat the pork with the spice mixture and nestle in the vegetables.
Roast until the internal temperature of the pork registers 145° F, 20 to 25 minutes, and the vegetables are tender. Let rest for 5 minutes; slice.
Serve the pork and vegetables with the mustard, sprinkled with the parsley.