Position an oven rack in the top third of the oven and preheat to 220°C. Prepare the wild rice as per package instructions (discarding any included flavor packets). Keep warm and set aside.
Meanwhile, toss the cabbage, garlic, 1 tablespoon of the oil, 1 tablespoon of the vinegar, 1/4 teaspoon salt and a few grinds of pepper together on a baking sheet. Spread out leaving room for the pork tenderloin in the center.
Sprinkle the pork with 3/4 teaspoon of the apple pie spice, 1/2 teaspoon salt and a few grinds of pepper. Heat the remaining 1 1/2 teaspoons oil in a large nonstick frying pan. Add the pork and cook, turning as needed, until brown on all sides, about 5 minutes. Place on the baking sheet and brush the top and sides of the pork with 2 teaspoons of the mustard. Roast until the cabbage is tender and the internal temperature of the pork registers 62°C on an instant-read thermometer, 25 to 30 minutes. Transfer the pork to a cutting board to rest for a few minutes and then slice. Toss the parsley with the cabbage.
Toss the apples with the remaining 1/4 teaspoon apple pie spice. For the sauce, stir together the sour cream and the remaining 2 teaspoons mustard and 1 teaspoon vinegar. Divide the rice, cabbage, pork and apples evenly among four dinner plates. Spoon the sauce over the pork. Serve each with a glass of milk.