Coat a large frying pan with nonstick spray. Crumble the beef into the pan. Add the onions, celery, and mushrooms. Cook over medium-high heat, breaking up the mixture with a wooden spoon, for 4 to 5 minutes, or until the meat is lightly browned.
Stir in the broth, thyme, caraway seeds and noodles. Bring to a boil. Reduce the heat, cover and simmer for 5 to 8 minutes, or until the noodles are just tender.
Stir in the paprika and tomato paste. Cover and simmer for 5 minutes.
Remove from the heat, stir in the yogurt and serve.