Heat the olive oil in a stock pan over medium high heat; pat the beef cubes dry, then add beef to the oil and saute till brown. Remove beef to drain on paper towels.
Add the onions and mushrooms to the pan and saute till the onions are golden.
Return the beef to the pot, and add carrots, barley, broth, wine and seasonings, and stir well.
Bring to a boil, then reduce heat to simmer and simmer till beef and barley are tender, about 45 minutes.
Stir in the peas, cook briefly till heated through, then add lemon juice.