Begin by cutting 2 pounds of beef chuck roast into 1-inch cubes for even cooking. Make sure each piece is roughly the same size to ensure uniform tenderness.

In a large skillet, heat 2 tablespoons of oil over medium-high heat. Add the cubed beef in batches, making sure not to overcrowd the pan, and sear on all sides until browned—about 3-4 minutes per side.

Using the same skillet, add the finely chopped onion and minced garlic, sautéing for 3-4 minutes until the onion turns translucent. Next, stir in the sliced mushrooms and continue cooking for another 2-3 minutes until they soften and release their liquid.

In your slow cooker, place the seared beef along with the sautéed onion, garlic, and mushrooms. Pour in 3 cups of beef broth and 2 tablespoons of Worcestershire sauce. Add in the Dijon mustard, dried thyme, and paprika, then season with salt and pepper. Mix everything thoroughly.

Cover your slow cooker and set it to cook on low for 7-8 hours or on high for 4-5 hours.

About 30 minutes before serving, mix 1 cup of sour cream with 2 tablespoons of all-purpose flour until smooth. Gently stir this mixture into the slow cooker.

When the cooking time is complete, ladle the Stroganoff over a bed of egg noodles or rice, and sprinkle chopped parsley on top before serving.