In a mixing bowl, combine olive oil, red wine vinegar, minced garlic, oregano, salt, and pepper. Add the flank steak and coat well. Marinate for at least 15 minutes.

Preheat the grill to medium-high heat. Remove steak from marinade and grill for about 5-7 minutes on each side for medium-rare, or until desired doneness. Let it rest for 5 minutes before slicing.

In a small bowl, whisk together olive oil, lemon juice, dijon mustard, honey, salt, and pepper until well combined.

In serving bowls, layer cooked quinoa, sliced steak, cherry tomatoes, cucumber, red onion, feta cheese, olives, and parsley. Drizzle with dressing before serving.