Heat the olive oil in a large Dutch oven over medium-high heat. Season the beef with salt and pepper and sear in batches until browned, 5–7 minutes. Transfer to a plate.
Add onion, carrots, and celery. Cook 4–5 minutes. Stir in garlic and cook 30 seconds.
Add red wine (or ½ cup broth) and scrape up the browned bits. Simmer 2–3 minutes.
Return the beef to the pot. Add potatoes, squash, green beans, thyme, rosemary, salt, and pepper. Pour in the beef broth.
Bring to a boil, reduce to low, cover, and simmer 1½–2 hours until the beef is fork-tender.
Stir in the frozen peas and cook 5 minutes.
Optional: whisk flour with 3 tablespoons cold water, stir in, and simmer uncovered 5–10 minutes to thicken.
Season to taste and serve with parsley.