Heat oil in heavy-bottomed medium-size pan.
Add shallot and mushrooms and saute over medium heat until tender, about 5 minutes.
Add barley and cook over low heat 1 to 2 minutes or until glistening.
Add wine and cook over medium heat until wine evaporates.
Add chicken broth and bring to boil.
Reduce heat to low. Simmer, covered, until liquid is absorbed and barley is tender but still chewy, 35 to 40 minutes.
Stir in cheese, tomatoes, walnuts and season to taste with salt and pepper.