In a large soup pot, heat oil over medium heat. Add pork tenderloin (in batches if necessary) and brown on all sides. Using a slotted spoon transfer pork to a dish and set aside. Add onions and garlic to pot and sauté over medium-low heat, stirring occasionally, until onions are golden, about 6 minutes.
Stir in the flour, paprika, and caraway seeds. Cook, stirring, for 2 minutes. Stir in wine and bring the mixture to a boil. Add tomato paste, bell pepper, potato, tomatoes, and chicken broth. Return pork to the pot and stir to blend. Reduce heat and simmer, partially covered, until pork is tender, about 1 hour. Season with salt (if using) and pepper to taste.
Meanwhile, cook noodles according to package directions until al dente. Drain and divide noodles between soup bowls. Top with hot soup. If desired, garnish each serving with a dollop of sour cream.