In a small glass bowl, whisk together 0.5 tbsp of olive oil, lemon juice, lemon zest, oregano, garlic powder, salt, and pepper to create the marinade.
Place the chicken breasts in a shallow dish and pour the marinade over them, ensuring each piece is thoroughly coated; let marinate for at least 15 minutes.
Preheat your grill or a heavy-bottomed grill pan over medium-high heat until hot.
Trim the woody ends off the asparagus and toss the spears with the remaining 0.5 tbsp of olive oil and a tiny pinch of sea salt.
Place the chicken on the grill and cook for 6 to 7 minutes per side, or until the internal temperature reaches a safe 165°F.
During the last 5 minutes of chicken cooking, add the asparagus to the grill and cook, turning occasionally, until tender-crisp and lightly charred.
Remove the chicken and let it rest for 3 minutes before slicing.
Serve the grilled chicken and charred asparagus over a bed of warm, fluffy cooked quinoa.