Whisk olive oil, oregano, garlic, salt, and pepper in a bowl and marinate steak for 30 minutes.
Cook pearl couscous in salted water according to package instructions then drain and set aside.
Heat a cast-iron skillet over medium-high heat and sear steak for 4 minutes per side until internal temperature reaches 135°F.
Rest the steak on a cutting board for 10 minutes then slice against the grain into thin strips.
Combine cucumber, tomatoes, and red onion in a separate mixing bowl.
Distribute cooked couscous evenly among four meal prep containers.
Layer sliced steak and vegetable mixture over the couscous base.
Top each bowl with olives, feta cheese, and a dollop of tzatziki before garnishing with parsley.