Heat 1 tsp of the oil in a heavy, medium saucepan and stir in the farro. Cook, stirring for about 3 minutes to toast them.
Add the remaining olive oil and onion and saute the mixture for about 3 minutes, until the onion is soft. Add the mushrooms and cook the mixture for another 3 minutes or until the mushrooms are soft. Add the broth, pepper and salt.
Bring the mixture to a boil, reduce heat, cover and simmer the pilaf for about 40 minutes, stirring occasionally.
Remove the pilaf from the heat, stir in parsley. Season with lemon juice, if desired. Garnish with tomatoes.