How to Make It
Place chicken and 1/4 cup Lemon Vinaigrette in a 1-gal. zip-top plastic freezer bag. Seal and turn to coat. Chill 30 minutes. (Reserve and chill remaining vinaigrette.)
Meanwhile, cook farro according to package directions, adding 1 tsp. salt and 2 garlic cloves before bringing to a boil. Drain and rinse; discard garlic, and transfer farro to a large bowl.
Preheat grill to 350° to 400° (medium-high) heat. Remove chicken from marinade, discarding marinade in bag. Sprinkle chicken with 1/4 tsp. each salt and black pepper. Grill chicken, covered with grill lid, 4 to 5 minutes on each side or until done. Transfer to a platter; cover with foil.
Toss together onion, next 3 ingredients, and remaining 1 tsp. salt and 1/2 tsp. black pepper. Place vegetables in a large grill basket, and grill, covered with grill lid, 10 to 12 minutes or until vegetables start to char and soften, stirring and turning every 2 minutes. Transfer vegetables to bowl, and cover with foil.
Coarsely chop chicken; toss with farro, vegetables, parsley, basil, thyme, and 1/4 cup chilled reserved Lemon Vinaigrette. Season with salt and pepper, and serve with remaining vinaigrette.