Cut the beef into 1 inch cubes and pat completely dry. Discard any large pieces of fat but marbleized fat is totally fine and adds great flavor. Season with garlic salt and pepper, then sprinkle with flour and toss to coat.
Season with garlic salt and pepper, then sprinkle with flour and toss to coat the meat.
Heat 2 tablespoons of olive oil or beef tallow in a skillet over medium high heat. Sear the meat in batches for about 45 seconds per side until browned but not cooked through. Remove with tongs and set aside on a plate. Add more oil between batches as needed.
Add 1 tablespoon of butter and the white wine to the skillet over medium heat. Use a silicone spatula to deglaze the bottom of the pan and scrape up all those browned bits because that is where the flavor is.
Add the onions and mushrooms and cook for 4-5 minutes.
Add the garlic and cook for one more minute then remove from heat.
Add the beef broth, bouillon, red wine vinegar, Worcestershire sauce, and Dijon mustard to the slow cooker and stir to combine.
Add the seared beef along with any juices from the plate then add the onion, mushroom, and garlic mixture. Add in your bone in if you are using one.
Cook on high for 4 to 5 hours or on low for 8 to 9 hours. Low and slow is my prefernce!
Remove the bone
Mix the cornstarch and cold water in a small dish, Then whisk it into the slow cooker. Switch the heat to warm.
Add the sour cream and cream of mushroom soup to a medium bowl and mix about 1 cup of the liquid from the slow cooker into the bowl.
Stir the mixture into the slow cooker.
Serve over cooked egg noodles.