Trim fat from roast. Cut roast into 2-inch cubes.
In a large bowl combine paprika, caraway seeds, garlic powder, pepper and salt. Add pork cubes and toss to coat.
In a large skillet cook pork, half at a time, in hot oil over medium heat until browned, turning occasionally.
Transfer pork to a 3 ½- or 4-quart slow cooker.
Add celery, carrots, parsnips, onion and tomatoes. Pour the water over all in cooker.
Cover and cook on low-heat setting for 5 to 6 hours or on high-heat setting for 2 ½ to 3 hours.
If using low-heat setting, turn to high-heat setting. Stir noodles into pork mixture in cooker.
Cover and cook on high-heat setting for 30 minutes more or until noodles are tender, stirring once halfway through cooking.
Top each serving with 1 tablespoon sour cream. If desired, sprinkle each serving with paprika.
