Place farro in a medium saucepan with water to cover by at least three inches and a pinch of salt. Bring to a boil, lower to a simmer and cook until tender, about 25 minutes. Drain well. If using right away, rinse with cold water to cool down.In a medium bowl or a glass jar with a fitted lid, combine all dressing ingredients.Place the arugula, farro, chives, and peaches in a serving bowl and drizzle with enough dressing to lightly coat. Toss gently.Add chopped nuts and/or crumbled cheese, if desired.