Coat the beef. Pat beef dry. Season generously with salt and pepper, then toss with flour until lightly coated.
Brown the beef. Heat olive oil (and butter if using) in a large Dutch oven over medium-high heat. Brown beef in batches, 3 to 4 minutes per side. Transfer browned beef to a plate.
Sauté aromatics. Add onion, carrots, and celery to the pot with a pinch of salt. Cook 6 to 8 minutes until softened. Add garlic and cook 30 seconds.
Build flavor. Stir in tomato paste and cook 1 minute. Add wine (if using) and scrape up browned bits from the bottom of the pot. Simmer 1 to 2 minutes.
Simmer. Add broth, Worcestershire, thyme, bay leaf, and the browned beef (plus any juices). Bring to a gentle simmer, then reduce heat to low. Cover and cook 1 hour 30 minutes.
Add potatoes. Stir in potatoes, cover, and simmer 45 to 60 minutes more, until beef is fork-tender and potatoes are cooked.
Finish. Stir in peas (if using) for 2 to 3 minutes. Taste and adjust salt and pepper. For a thicker stew, stir in cornstarch slurry and simmer 2 minutes.
Serve. Remove bay leaf, garnish with parsley, and serve hot.