Start by combining the flour, garlic powder, salt, and black pepper in a bowl. Toss the beef cubes in this mixture until they are well coated.
In a large Dutch oven or pot, heat the olive oil over medium heat. Add the beef and onions, cooking until the beef is browned on all sides and the onions are translucent.
Pour in the beef broth and red wine, making sure to scrape up any browned bits from the bottom of the pot to enhance the flavor.
Add the potatoes, carrots, celery, tomato paste, and rosemary to the pot. Stir well, then reduce the heat to medium-low. Cover the pot and let it simmer for about an hour, or until the beef is tender. This may take up to 90 minutes.
In a small bowl, mix equal parts cornstarch and water to create a slurry. Gradually add this slurry to the boiling stew, stirring continuously until the stew reaches your desired thickness. You may not need all of the slurry, or you might want to add more for a thicker consistency.
Finally, stir in the peas and let the stew simmer for an additional 5-10 minutes. Season with salt and pepper to taste before serving.
Enjoy a hearty bowl of this delicious beef stew, perfect for a comforting meal on a chilly day.