Brown the ground beef in a large sauce pan.
While the ground beef is browning, add the cornstarch to the chicken broth, stir this chicken broth mixture well, and allow the cornstarch to dissolve.
Also while waiting for the ground beef to brown, take this time to slice the mushrooms (if you have not already done so).
After the ground beef has browned, drain the excess fat off the ground beef.
Then add the chicken broth cornstarch mixture, mushrooms, garlic, ¾ cup of white wine, pepper, and deli mustard to the pan of cooked ground beef.
Stir the mixture, cover the pan with a lid, and cook the mixture on medium low heat for 20 minutes.
Occasionally stir the mixture throughout the 20 minute cooking time.
After the mixture has cooked for 20 minutes, remove the pan from the heat, then add the sour cream and the remaining 2 tablespoons of white wine.
Salt the stroganoff mixture to taste. Serve over eggs noodles or rice.
Garnish with optional parsley.