In a medium saucepan, bring farro, apple cider, salt, bay leaves and 2 cups water to a simmer. Simmer until farro is tender and liquid evaporates, about 30 minutes. If all the liquid evaporates before the farro is done, add a little more water. Let farro cool, and then discard bay leaves. In a salad bowl, whisk together olive oil, lemon juice and a pinch of salt. Add farro, cheese, and pistachio nuts and mix well. This salad base will keep for up to 4 hours at room temperature or overnight in the refrigerator (bring to room temperature before serving). Just before serving, fold in arugula, herbs, tomatoes, radish and flaky salt to taste.