01 - Season beef cubes evenly with salt and freshly ground black pepper.
02 - Heat olive oil in a large skillet over medium-high heat. Brown beef cubes in batches for 3 to 4 minutes per batch, ensuring all sides are seared. Transfer browned beef to slow cooker.
03 - Place carrots, potatoes, celery, onion, and garlic into the slow cooker over the seared beef.
04 - In a mixing bowl, whisk together beef broth, tomato paste, Worcestershire sauce, and red wine if used. Pour mixture evenly over beef and vegetables in the slow cooker.
05 - Incorporate dried thyme, dried rosemary, and bay leaves into the slow cooker. Gently stir to combine all ingredients evenly.
06 - Cover and cook on low setting for 8 hours or on high for 4 to 5 hours until beef and vegetables are tender.
07 - About 30 minutes before serving, mix cornstarch or gluten-free flour with water to create a slurry. Stir slurry into stew along with frozen peas. Recover and continue cooking for 30 minutes until the stew thickens.
08 - Remove bay leaves from stew. Taste and adjust salt and pepper as needed before serving.