In a large saute pan, heat the olive oil over medium low. Add the mushrooms along with a pinch of salt and cook until their water has released and the mushrooms are slightly darker, soft, and fragrant, approximately 5 minutes. Add the garlic and cook for another 1-2 minutes.
In a large bowl, toss together the mushrooms, farro, walnuts, walnut oil, lemon juice and parsley. Season with salt and pepper to taste.