How to Make It
Combine water and diced sweet potato in a medium saucepan over medium-high. Bring to a boil; reduce heat to medium-low, and cook 3 minutes. Stir in chopped rainbow chard. Cook until wilted, about 2 minutes; drain well.
Combine chard mixture, hot cooked farro, extra-virgin olive oil, tarragon vinegar, kosher salt, and black pepper in a medium bowl; toss to combine. Sprinkle with sliced scallions.