In a large skillet or cast iron skillet, melt tablespoons of butter over medium-high heat.
Sear the venison strips until they reach your desired doneness.
Once seared, remove the venison and set it aside. It's important to keep all the browned bits at the bottom of the pan, as they'll add great flavor to the sauce.
In the same skillet, add another tablespoon of butter. Add diced onions, minced garlic, and sliced mushrooms, cooking them over medium heat until the onions are soft and translucent.
Stir in a tablespoon of all-purpose flour, making sure it's well incorporated with the onion and mushroom mixture. This flour mixture will help thicken the sauce.
Slowly whisk in a cup of beef broth, followed by half a cup of heavy cream.
Let the mixture thicken, stirring with a wooden spoon.
Stir in the sour cream, Worcestershire sauce, and Dijon mustard.
Season with salt and black pepper to taste.
Return the venison and any accumulated juices to the pan. Let it simmer on low heat until the meat is heated through.
Serve over a bed of rice, egg noodles or mashed potatoes.
