Place steaks in between plastic wrap, and pound them on both sides with a meat mallet until thin. Mix flour, salt and pepper together in a deep plate. Dredge pounded steaks with flour mixture.
Heat oil on medium/high until hot. Fry steaks on both sides, giving them a nice sear. Remove steaks and set aside. Add onions and mushrooms and cook until mostly soft. Add wine, scraping up any brown bits stuck to pan. Stir in beef bouillon to taste (should taste rich). Add more water or wine if needed. Bring to a simmer then stir in heavy cream. Add back in the steaks, more cracked pepper if desired, cover and cook an additional 20-30 minutes on low. Steak should be tender enough to cut it with a fork. Serve with mashed potatoes.
This recipe is great for tough or gamey White-tailed deer.