1. Pat the beef cubes dry with paper towels, then place them in a bowl and season with 1 teaspoon kosher salt, ½ teaspoon black pepper, and the flour. Toss until the beef is evenly coated.

2. Heat the olive oil in a large skillet over medium high heat. Working in batches, sear the floured beef cubes until browned on at least two sides, about 3 to 4 minutes per batch. Transfer the browned beef to the crockpot.

3. In the same skillet, add the chopped onion, celery, and mushrooms. Cook for 4 to 5 minutes, stirring often, until the onions soften and the vegetables begin to brown. Add the minced garlic and cook for 30 seconds until fragrant.

4. Stir the tomato paste into the vegetables and cook for 1 minute. Pour in the beef broth, Worcestershire sauce, and soy sauce if using. Scrape up any browned bits from the bottom of the pan, then bring the mixture just to a simmer.

5. Pour the hot broth and vegetable mixture over the browned beef in the crockpot. Add the carrots and potatoes, then sprinkle in the remaining ½ teaspoon kosher salt, remaining ½ teaspoon black pepper, dried thyme, dried rosemary, paprika, and bay leaves. Gently stir to combine.

6. Cover the crockpot and cook on LOW for 7 to 8 hours or on HIGH for 4 to 5 hours, until the beef is fork tender and the vegetables are cooked through but not falling apart.

7. If you prefer a thicker gravy, whisk the cornstarch and cold water together in a small bowl to make a slurry. Stir the slurry into the hot stew, cover, and cook on HIGH for an additional 15 to 20 minutes or until the liquid thickens.

8. Remove the bay leaves. Taste the stew and adjust seasoning with additional salt and pepper if needed. Stir in the chopped fresh parsley right before serving and ladle into warm bowls.