Heat the oven to 350 degrees F.

In a medium saucepan, combine the farro and enough cold water to cover it by about an inch. Soak for 20 minutes. Drain well and return the farro to the pan, again covering it with cold water. Add a few generous pinches of salt and bring to a boil over high heat. Lower the heat, cover and simmer for 20 minutes, until the farro is tender but still has some bite.

While the farro is cooking, clean mushrooms and cut them into bite-sized pieces – halved or quartered depending on size of the mushrooms. Arrange on a rimmed baking sheet and lightly drizzle with olive oil. Sprinkle with salt and pepper, and toss gently to distribute everything. Spread the mushrooms out evenly on the baking sheet and put in the oven for about 20-30 minutes, stirring halfway through, until crisp around the edges and cooked through.

When the farro is cooked, drain it well and spread it on a clean baking sheet to cool. Cool the mushrooms once they are cooked.

When the farro and mushrooms are close to room temperature, combine them in a serving bowl. Add the lemon zest, lemon juice and 3 tablespoons of olive oil (add more if desired), tossing gently to combine. Add the arugula, Parmesan, parsley and a generous grinding of pepper and mix gently. Adjust seasonings if necessary.

Serve at room temperature.