In a medium saucepan, combine 1 cup farro, 1 cup apple cider, 2 cups water, 2 bay leaves, and kosher salt. Bring the mixture to a boil, then reduce the heat and simmer uncovered until the farro is tender, which typically takes about 30 minutes.
Drain the cooked farro well, discard the bay leaves, and transfer the hot grains to a large mixing bowl.
In a separate small bowl or measuring cup, whisk together the extra virgin olive oil, fresh lemon juice, salt, and pepper to create a simple vinaigrette.
Pour the dressing over the warm farro and toss well so the grains absorb the dressing, then let it sit for at least 15 minutes to cool.
Once cooled, stir in the roasted pistachios, chopped fresh parsley, chopped mint, halved cherry tomatoes, and sliced radishes.
Just before serving, add the baby arugula and shaved Parmesan cheese, folding them in gently so the cheese does not break apart. Finish with a sprinkle of flaky sea salt like Maldon.