Heat a skillet over medium heat and brown the ground beef until fully cooked. Drain any excess fat from the skillet.
Transfer the cooked ground beef to the slow cooker.
In the same skillet, add the diced onion and minced garlic. Sauté until the onion becomes translucent and the garlic is fragrant, about 2-3 minutes.
Add the sautéed onion and garlic to the slow cooker with the ground beef.
Add the condensed cream of mushroom soup, beef broth, Worcestershire sauce, Dijon mustard, and sliced mushrooms to the slow cooker. Stir well to combine all the ingredients.
Season with salt and pepper according to your taste.
Cover the slow cooker and cook on low heat for 6-8 hours or on high heat for 3-4 hours. This allows the flavors to meld together and the meat to become tender.
Just before serving, stir in the sour cream until well incorporated into the sauce.
Serve the Poor Man’s Stroganoff over cooked egg noodles or rice.
Garnish with freshly chopped parsley, if desired.
