Season the chicken breast evenly on both sides with the dried oregano, sea salt, and black pepper.
Heat half of the olive oil in a skillet over medium-high heat. Add the chicken and cook for 6-7 minutes per side until golden brown and cooked through.
While the chicken cooks, dice the cucumber and halve the cherry tomatoes. Finely chop the fresh parsley and mince the garlic clove.
In a small bowl, whisk together the remaining olive oil, lemon juice, and minced garlic to create the dressing.
Once the chicken is finished, let it rest for 3 minutes before slicing it into bite-sized strips.
In a large bowl, combine the cooked quinoa, cucumber, cherry tomatoes, and parsley.
Add the sliced chicken to the bowl, pour the lemon dressing over the top, and toss gently to combine before serving.