Season the flank steak on both sides with salt, pepper, and half of the dried oregano.
Heat 1 tablespoon of olive oil in a cast-iron skillet over medium-high heat.
Sear the steak for 4 to 5 minutes per side until an internal temperature of 135 degrees Fahrenheit is reached for medium-rare.
Transfer the steak to a cutting board and let rest for 10 minutes before slicing thinly against the grain.
In a small container, whisk the remaining olive oil, lemon juice, and remaining oregano to emulsify the dressing.
Distribute the cooked quinoa evenly between two bowls.
Arrange the sliced steak, tomatoes, cucumbers, red onions, and olives atop the quinoa base.
Sprinkle with crumbled feta cheese and drizzle with the prepared lemon-herb dressing.
Garnish with fresh parsley and serve.