In a large bowl, combine all-purpose flour, garlic powder, salt, and black pepper. Toss the cubed stewing beef in this mixture until coated evenly. Set aside.

Heat olive oil in a large heavy pot over medium-high heat. Brown the beef in batches for about 3-4 minutes on each side. Remove and set aside.

In the same pot, add more olive oil if needed and sauté the chopped onion for approximately 3 minutes until translucent and fragrant.

Pour in the beef broth and optional red wine while scraping up any browned bits from the bottom. Bring to a gentle simmer for 2-3 minutes.

Return the browned beef to the pot and add chopped potatoes, carrots, celery, tomato paste, and rosemary. Stir to combine.

Reduce heat to low, cover, and let it simmer for 1 to 1.5 hours until beef is fork-tender.

Mix equal parts cornstarch and water in a small bowl to create a slurry. Gradually add to the stew, stirring continuously. Simmer for an additional 5-10 minutes.

Stir in the peas and cook for an additional 5 minutes. Adjust seasoning with salt and pepper if needed.

Ladle the hearty beef stew into bowls and serve hot with homemade bread or over rice.