Preheat your oven to 400°F (200°C). In a bowl, mix olive oil, oregano, garlic powder, salt, and pepper. Coat the chicken breasts with this mixture and place them on a baking tray.
Bake the chicken in the preheated oven for 20-25 minutes or until fully cooked (internal temperature of 165°F/75°C). Remove from the oven and let it rest for 5 minutes.
While the chicken bakes, rinse the quinoa under cold water. Cook it according to package instructions. Typically, combine 1 cup of quinoa with 2 cups of water in a saucepan, bring to a boil, reduce heat, cover, and simmer for about 15 minutes. Once done, fluff with a fork.
While the quinoa is cooking, prepare the vegetables: chop the cherry tomatoes, cucumber, and red bell pepper, and slice the Kalamata olives.
Once the chicken has rested, slice it into strips or cubes.
In meal prep containers, divide the cooked quinoa evenly. Top with the sliced chicken, cherry tomatoes, cucumber, red bell pepper, Kalamata olives, and crumbled feta cheese.
Drizzle the lemon juice over each bowl.
Garnish with chopped fresh parsley before sealing the containers.