Preparation:
- Season the beef: In a large bowl, season the beef stew meat with salt, pepper, and paprika. Toss the meat to ensure even seasoning.
- Sear the beef: Heat olive oil in a large skillet over medium-high heat. Work in batches, sear the beef cubes on all sides until browned. This step helps seal in the juices and adds a rich flavor to the final dish.
- Prepare the slow cooker: Place the diced onions, minced garlic, and sliced mushrooms in the slow cooker. Add the seared beef cubes on top.
- Prepare the sauce: In a separate bowl, whisk together the beef broth, red wine (if using), Worcestershire sauce, tomato paste, soy sauce, Dijon mustard, dried thyme, and a pinch of salt and pepper, and pour the sauce over the beef in the slow cooker.
- Cook on low heat: Set the slow cooker to low heat and cook for 6-8 hours or until the beef is fork-tender and the flavors have melded together. The low and slow cooking process will ensure the beef becomes incredibly tender.
- Thicken the sauce: In a small bowl, mix the all-purpose flour with a few tablespoons of water to create a slurry. Stir the slurry into the slow cooker, mixing well to combine. Continue cooking for an additional 30 minutes or until the sauce has thickened to your desired consistency.
- Serve and garnish: Serve the slow cooker beef tips over mashed potatoes, rice, or noodles, and garnish with chopped fresh parsley if desired. The dish pairs well with steamed vegetables or a crisp green salad.