Heat a large skillet over medium high heat and cook Gary's QuickSteak according to package directions, using the seasoning packet included in the package. Remove from pan and set aside.
Reduce heat to medium and add the butter and olive oil to the pan. Add the mushrooms and onions and cook 6 - 8 minutes, until softened.
Add the garlic and cook another minute, until fragrant.
Add the flour and cook for one minute.
Stir in the beef broth, Worcestershire sauce Dijon mustard, thyme, salt and black pepper. Bring to a boil then reduce heat and simmer for 5 - 6 minutes until thickened slightly.
Add the cooked Gary's QuickSteak to the mixture and cook for another 1 - 2 minutes, until heated through.
Remove from heat, stir in the sour cream and season to taste.
Serve the Stroganoff over cooked egg noodles or mashed potatoes. Garnish with parsley if desired.