Preheat oven to 300°.
In a mixing bowl, combine the cabbage, onions, apple, brown sugar, garlic, nutmeg, caraway seeds, and vinegar with a ½ cup of the stock. Mix well.
Season with salt and pepper and transfer to a large, buttered casserole dish. Cover and place it in the oven. Cook for 1½ hours, stirring the contents of the casserole dish frequently.
Turn off the oven and open the door slightly.
When the dish has cooled, remove it from the oven and set aside. Preheat oven to 450°.
In a medium sauté pan, add the olive oil and warm over medium heat. Season the sirloin with salt and pepper and then add to pan. Cook until golden brown on both sides. Remove sirloin from the pan and set aside.
Spoon the cabbage into a large saucepan. Add the remaining stock and bring to a boil. Reduce heat so that the soup simmers.
Place the sirloin in the oven and cook until it is the desired level of doneness.
Remove the sirloin from the oven and let stand for 5 minutes. Ladle the soup into serving bowls. Thinly slice the steak and place it on top of the soup. Serve with Horseradish Cream and watercress.