Heat oil in a large nonstick skillet over medium-high heat. Sprinkle pork with salt and pepper. Add pork to pan; sauté 2 minutes. Remove pork from pan, and keep warm.
Add apple, onion, and bay leaf to pan; cook 2 minutes or until onion is lightly browned. Add beer, scraping pan to loosen browned bits. Add sauerkraut and sausage; bring to a simmer, and cook 5 minutes. Return pork to pan; cover and cook 2 minutes or until pork is thoroughly heated. Discard bay leaf. Stir in parsley. Serve with horseradish and mustard.