Cook meat in a large skillet, breaking it up with a spoon as it cooks, until no pink remains. Drain. Stir in onion; cook until tender, about 3 minutes. Blend in broth, mustard and tomato paste. Bring to boil; lower heat and cover and simmer 5 minutes. Stir in sour cream very slowly to prevent curdling. Continue to heat gently, but do not allow to boil. Serve over hot cooked noodles.
TDS 3