Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Rinse the quinoa under cold water, then combine it with 0.5 cup of water in a small saucepan; bring to a boil, reduce heat to low, cover, and simmer for 15 minutes.
In a small bowl, whisk together the extra virgin olive oil, lemon juice, garlic powder, dried oregano, sea salt, and black pepper to create the marinade.
Place the chicken breast and asparagus spears on the prepared baking sheet, ensuring they are in a single layer.
Brush the lemon-herb marinade generously over both the chicken and the asparagus until evenly coated.
Roast in the oven for 18 to 20 minutes, or until the chicken reaches an internal temperature of 165°F and the asparagus is tender.
Remove from the oven and let the chicken rest for 5 minutes before slicing.
Fluff the cooked quinoa with a fork and serve it alongside the sliced chicken and roasted asparagus.