In a small pot, boil 2 cups of water. Add the dried porcini mushrooms, cover, turn off the heat and set aside for 30 minutes.
In a dutch oven, heat the olive oil and butter. Add the onions and saute until soft, about 10 minutes.
Add the garlic and sauté for 1 minute.
Add the fresh mushrooms and cook until soft, about 10 minutes.
Add the rinsed farro and sauté for an additional 5 minutes.
Stir in the chicken broth, cover and turn the heat to medium high.
Drain the porcini mushrooms and reserve the water.
Strain the porcini water with a fine sieve to remove any grit, then add the liquid to the soup.
Season with salt and pepper to taste, cover and lower the heat to simmer for about 45 minutes, or until the farro is tender.
Stir occasionally and add additional seasoning if necessary.
Serve in warmed bowls, sprinkled with the chopped parsley, with slices of grilled ciabatta bread on the side.