This green bean salad packs a punch full of fresh flavors! Charred green beans offer a contrasting taste against the tart marinated red onion and balsamic vinaigrette dressing and salty shaved Parmigiano-Reggiano.
Heat oven to 400 degrees. Remove loose outer skins from the garlic bulb and slice top off the top 1/4 inch so tops of individual cloves are exposed. Drizzle 1 teaspoon of olive oil over the cut surface and wrap bulb in foil. Bake for 40 minutes and remove from over. Pull off 4 medium-size cloves, squeeze out of skins and mash on a cutting board with the side of a knife. Reserve remaining roasted garlic for another use.
Meanwhile, rinse dried farro and add to a small saucepan with 1/2 cup water. Bring to a boil, reduce heat and simmer until just tender and water is absorbed, 25-30 minutes. If the heat is too high and your water boils off early add additional water 1/4 cup at a time as needed. Remove from heat and reserve.
Switch oven to broiler and place rack in top position. Toss green beans with 2 teaspoons olive oil, 1/4 teaspoon salt, 1/4 teaspoon black pepper and garlic powder. Spread beans out on a broiler-safe pan and cook until beans start to char and blister, about 3 minutes. Turn beans and roast an additional 2-3 minutes until tender. Remove from broiler and reserve.
Combining remaining salt and pepper with mashed roasted garlic, red wine vinegar, water, mustard, and simple syrup to make a marinade and pour the liquid into a flat-bottomed dish. Add onions and cooked farro to the marinade, being careful to keep them separate. Divide roasted green beans into 4 plates. Top each pile of beans with 1/4 of the marinated farro. Top that with a tangle of the sliced red onions. Sprinkle cheese over the salad and finish each serving with a tablespoon of the remaining olive oil drizzled on top.
Note: Sugar simple syrup is made by combining equal parts of sugar and water and heated until the sugar dissolves.