Heat the oil over medium heat in a large, heavy nonstick skillet. Add the onion. Cook, stirring, until it begins to soften, about three minutes. Add the fresh mushrooms. Cook, stirring, until they begin to soften and sweat. Add salt to taste, the garlic and rosemary. Continue to cook, stirring often, until the mushrooms are tender, about five minutes. Add the farro and reconstituted dried mushrooms. Cook, stirring, until the grains of farro are separate and beginning to crackle, about two minutes. Stir in the wine and cook, stirring until the wine has been absorbed. Add all but about 1 cup of the stock, and bring to a simmer. Cover and simmer 50 minutes or until the farro is tender; some of the grains will be beginning to splay. Remove the lid, and stir vigorously from time to time. Taste and adjust seasoning. There should be some liquid remaining in the pot but not too much. If the farro is submerged in stock, raise the heat and cook until there is just enough to moisten the grains, like a sauce. If there is not, stir in the remaining stock. If not serving right away, cover and let stand. Just before serving, bring back to a simmer, add the Parmesan, parsley and pepper, and stir together. Remove from the heat and serve.