Season beef with salt and pepper. Toss with flour.
Heat 2 tbsp oil in a skillet over medium-high. Sear beef in batches. Move to crockpot.
Add remaining oil and onion to skillet. Cook 4 minutes.
Stir in garlic and tomato paste. Cook 1 minute.
Add wine and scrape up browned bits. Simmer until reduced by half.
Pour into crockpot. Add broth, bouillon, Worcestershire, bay leaves, and thyme.
Add potatoes, carrots, and celery. Push vegetables down into the liquid.
Cover and cook on low 8 to 9 hours or high 6 to 7 hours, until beef is fork tender.
Remove bay leaves and thyme stems. Stir in peas. Cook 10 minutes.
Stir in butter. Season to taste. Top with parsley.