Season the chicken breast evenly on both sides with sea salt, black pepper, and dried oregano.
Heat a skillet over medium-high heat with 0.5 tablespoons of olive oil and sear the chicken for 5-7 minutes per side until fully cooked and golden.
While the chicken is resting, dice the cucumber, halve the cherry tomatoes, and finely mince the red onion and fresh parsley.
In a small jar or bowl, whisk together the remaining 0.5 tablespoons of olive oil with the lemon juice and half of the chopped parsley to create the dressing.
In a large mixing bowl, combine the cooked quinoa, cucumber, tomatoes, and red onion.
Slice the rested chicken into bite-sized strips and add it to the quinoa mixture.
Drizzle the lemon-herb dressing over the salad, sprinkle with the remaining parsley, and toss thoroughly before serving.