Rinse the quinoa under cold water, then combine with 0.5 cup water in a small pot; bring to a boil, reduce heat, cover, and simmer for 15 minutes until fluffy.
While quinoa cooks, season the chicken breast with half the olive oil, dried oregano, sea salt, and black pepper.
Heat a skillet over medium-high heat and sear the chicken for 6-7 minutes per side until cooked through and golden brown.
Dice the cucumber, halve the cherry tomatoes, and finely chop the fresh parsley.
In a medium bowl, whisk together the remaining olive oil and lemon juice to create a light dressing.
Toss the cooked quinoa with the chopped vegetables, parsley, and dressing until well combined.
Slice the chicken breast and serve it atop the quinoa salad, or pack into a container for a perfect meal-prep lunch.