Place beef cubes in a bowl. Season with salt and pepper. Sprinkle cornstarch over the meat and toss to coat.

Heat oil in a large pot, over high heat. Add meat to pot and brown on all sides (about 5-7 minutes total). Remove meat and set aside.

Return pot to burner and reduce to medium/high. Add onions, mushrooms, garlic and cook just until starting to soften, about 4 minutes. Add rosemary and bay leaf.

Pour in broth, cover and simmer (on low heat) 1 hour. After 1 hour, stir in barley, recover and continue to simmer another 45 minutes. Stir in defrosted peas and cook uncovered 10 minutes.

Serve hot.