01 - Pat beef cubes completely dry with paper towels. Toss beef in a bowl with flour, salt, and pepper until evenly coated.
02 - Heat vegetable oil in a large Dutch oven or heavy pot over medium-high heat. Brown beef cubes on all sides in batches to avoid overcrowding. Remove browned beef and set aside.
03 - In the same pot, add chopped onions and cook for 3 minutes until softened and translucent. Add minced garlic and cook for 1 minute until fragrant.
04 - Stir in carrots, parsnips, potatoes, and celery. Cook for 3 to 4 minutes, stirring occasionally, until vegetables begin to soften slightly.
05 - Return browned beef to the pot. Add rinsed pearl barley, bay leaves, thyme, and beef broth. Stir well to combine and bring mixture to a boil.
06 - Reduce heat to low, cover with a tight-fitting lid, and simmer for 1½ hours. Stir occasionally to prevent sticking and ensure even cooking.
07 - Remove lid and continue simmering uncovered for 30 minutes. This allows the stew to thicken naturally and flavors to meld together.
08 - Discard bay leaves. Stir in chopped parsley. Taste and adjust seasoning with additional salt and pepper as needed.
09 - Ladle hot stew into bowls and garnish with extra fresh parsley. Serve immediately with crusty bread.