Spray a large nonstick skillet with nonstick spray and set over medium-high heat. Add the beef and cook, stirring frequently to break it up, until browned, 6-8 minutes. Add the onion. Carrot, celery, bell pepper and garlic cook, stirring occasionally, until softened, about 5 minutes. Stir in the mushrooms, beef broth, tomato paste, basil and oregano; bring to a boil. Reduce the heat and gently simmer, covered, 15 minutes. Add the sour cream and cook, uncovered, until the sauce is thickened, about 25 minutes longer. Stir in the salt and pepper.