Rinse the pork knuckle under cold water and pat completely dry with paper towels. Score the skin in a crosshatch pattern using a sharp knife, being careful not to cut into the meat.

Rub the pork knuckle all over with salt, black pepper, caraway seeds, and minced garlic. Place in a roasting pan and refrigerate uncovered for 2-3 hours or overnight to dry out the skin.

Preheat oven to 350°F (175°C). Pour 2 cups of water into the bottom of the roasting pan, place the pork knuckle on a rack above the water, and cover tightly with foil.

Roast for 2 hours, then remove foil and increase temperature to 425°F (220°C). Continue roasting for 30-40 minutes until the skin is deeply golden and crispy.

While the pork roasts, prepare the red cabbage: Heat butter in a large pot, add sliced onions and cook until softened. Add shredded red cabbage, sliced apples, vinegar, brown sugar, bay leaves, and caraway seeds. Season with salt and pepper.

Add 1/2 cup water to the cabbage, cover and simmer on low heat for 45-60 minutes, stirring occasionally, until tender. Adjust seasoning with more vinegar or sugar to taste.

For the potato dumplings: Boil half the potatoes until tender, then drain and mash while hot. Peel and grate the remaining raw potatoes, squeeze out excess moisture using a clean kitchen towel.

Combine mashed and grated potatoes in a bowl with flour, egg, salt, and nutmeg. Mix until a soft dough forms. Shape into 8 round dumplings.

Bring a large pot of salted water to a gentle simmer. Carefully add dumplings and cook for 15-20 minutes until they float to the surface and are cooked through.

Remove pork knuckle from oven and let rest for 10 minutes. Serve sliced pork with crispy skin, red cabbage, and potato dumplings on the side.