In a small bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, dried oregano, sea salt, and black pepper to create the marinade.
Place the chicken breast in a shallow dish or resealable bag and pour half of the marinade over it, ensuring it is well coated. Let it marinate for at least 20 minutes.
Preheat your grill or grill pan over medium-high heat.
Place the chicken on the grill and cook for 6 to 7 minutes per side, or until the internal temperature reaches 165°F and the outside has beautiful char marks.
While the chicken is grilling, toss the asparagus spears in the remaining marinade and place them on the grill for 4 to 5 minutes until tender-crisp.
Fluff the pre-cooked quinoa and place it on a plate.
Slice the grilled chicken and serve it over the quinoa alongside the grilled asparagus.