This salad is a great barbecue side, or hearty enough for a stand-alone meal. At Elderslie Farm, chef Katharine Elder likes to keep a big batch on hand to eat for lunch.
In a large saucepan, cook farro in lightly salted water until tender but chewy, according to package directions. Drain (if necessary) and cool completely.
Make Lemon-Shallot Vinaigrette: Remove 1 teaspoon zest and squeeze 1/4 cup juice from lemon. In a medium bowl, whisk together shallot, lemon zest and lemon juice. Gradually whisk in olive oil until incorporated. Whisk in salt and pepper.
To assemble: Coarsely chop olives. In a large bowl, toss farro, olives, arugula, spinach, feta and the vinaigrette. Cover and refrigerate at least 1 hour or up to 2 days.