Whisk together all marinade ingredients. Pour over steak in a large ziploc bag. Seal and marinate in refrigerator, preferably overnight.
Whisk together dressing ingredients, set aside.
Rinse farro. In medium saucepan, combine with 3 cups water. Bring to boil, reduce heat and simmer, stirring occasionally. When farro reaches desired tenderness, about 15-20 minutes for pearled and 30-40 for un-pearled. Drain off excess water, set aside.
Remove meat from marinade, pat dry, place on hot grill and cook 4-5 minutes for medium rare. Remove from heat, cover with foil and rest for 5-10 minutes. Slice thinly against the grain.
Assemble salad, add steak, feta and dressing. Enjoy!
