Season the chicken breast evenly with half of the sea salt, black pepper, and dried oregano.
Heat a non-stick skillet over medium-high heat and cook the chicken for 5-7 minutes per side until the internal temperature reaches 165°F.
While the chicken cooks, dice the cucumber, halve the cherry tomatoes, and finely mince the red onion and fresh parsley.
In a small bowl, whisk together the extra virgin olive oil, fresh lemon juice, and the remaining salt, pepper, and oregano to create the vinaigrette.
Once the chicken is cooked, let it rest for 5 minutes before slicing into bite-sized strips.
In a large bowl or meal prep container, combine the cooked quinoa, baby spinach, diced cucumber, halved tomatoes, and minced red onion.
Add the sliced chicken and fresh parsley to the bowl, drizzle with the lemon vinaigrette, and toss thoroughly to combine.