Heat olive oil in a large heavy bottomed pot over medium heat. Season stew meat with salt and pepper, to taste. Add to the pot and cook for 6-8 minutes, flipping halfway through.
Add onion, carrots and celery. Cook, stirring occasionally, until tender, about 3-4 minutes. Add garlic and cook an additional minute.
Stir in wine, scraping any browned bits from the bottom of the stockpot. Stir in beef stock, thyme, and Italian seasoning. Bring to a boil.
Add the barley and reduce heat and simmer, for 5 minutes.
Add the frozen peas, stir, and cook an additional 5-10 minutes, or until the barley is tender. Add salt and pepper to taste.
Transfer about 1/2 cup of the liquid to a small bowl. Mix in the cornstarch and pour the liquid back into the stew. Stir for about a minute to allow the cornstarch to thicken the stew a bit.