Warm olive oil in a large skillet over medium heat.
Season beef with salt and pepper, to taste. Add beef to the skillet and cook until evenly browned, about 2-3 minutes.
Place beef, potatoes, carrots, onion, and garlic into a 6-quart slow cooker.
In a bowl, whisk together the beef broth, vegetable juice, tomato paste, Worcestershire, thyme, oregano, paprika, and mustard seeds until well combined; pour over the the beef and vegetables.
Toss in 2 bay leaves and season with salt and pepper, to taste.
Cover and cook on low heat for 7-8 hours.
In a small bowl, whisk together flour and ½ cup stew broth to create a slurry. Slowly stir the mixture into the slow cooker. Cover and cook on high heat for an additional 30 minutes, or until thickened.
During the last 5 minutes, stir in the peas.
Discard bay leaves and thyme sprig.
Serve immediately in bowls, garnished with parsley, if desired.
