Combine marinade ingredients in a large ziploc bag and shake well to coat. Refrigerate at least 4 hours or overnight.
Remove tenderloins from marinade and grill over medium heat for 8-10 minutes per side (or until internal temperature reaches 165 degrees F).
Cook farro according to package directions.
Combine chopped vegetables with feta and mix well.
Mix lettuce and spinach together and divide between 4 large bowls. Add 1/4 of the farro to each bowl. Top each bowl with 3/4 cup of vegetable mixture.
Once turkey is cooked, slice and divide among salads.
For the optional dressing, slowly add water to hummus and mix well until hummus reaches a pourable consistency or use your favorite dressing.