Prep the Meat. Start by trimming the excess fat off and cutting the beef into 1 ½ inch cubes. Season the meat with salt and black pepper.
Heat vegetable oil in a heavy-bottomed large skillet over medium-high heat. Sear the beef 4–5 minutes per side until deeply golden brown.
Work in batches so you don’t overcrowd the pan. Wipe the skillet clean if needed and add more oil before the next batch. Keep the heat steady and avoid overcooking.
Transfer the seared chunks into 4.5 quart slow cooker along with the browned bits from the pan.
Add the veggies (potatoes, carrots, mushrooms and onion). Sprinkle with spices.
In a small bowl or measuring cup mix beef broth, tomato sauce and Worcestershire sauce. Pour in the slow cooker and add 2 bay leaves.
Cook on LOW for 8 hours or HIGH 4 hours. After that taste for seasoning and add more salt/pepper if necessary.
Thicken the stew: Remove 2 cups of hot broth from the slow cooker. Whisk in ½ cup of all-purpose flour gradually until smooth and lump-free.
Pour the slurry back into the slow cooker and stir gently. Add green beans and cook on HIGH for 15 minutes or LOW for 30 minutes. Taste and adjust seasoning if needed.
Serve as it is or with a portion of rice or simple green salad.