How to Make It
Bring 3 cups water to a boil in a large saucepan over high.
Meanwhile, rinse farro under running water until water runs clear. Add farro to boiling water. Reduce heat to low; cover and simmer until farro is tender, about 25 minutes. Drain and spread in an even layer on a baking sheet lined with parchment paper; let stand until cool, about 1 hour. Or place in the refrigerator until cool, about 30 minutes.
Place oil, vinegar, mustard, shallot, salt, and pepper in a small jar with a tight-fitting lid; attach lid, and shake vigorously until combined.
Toss farro and arugula with 2 tablespoons of the dressing; spread on a large platter. Toss tomatoes, peaches, and basil with 3 tablespoons of the dressing, and spoon over the farro mixture. Top with crumbled ricotta salata, and serve with remaining dressing on the side.