Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Pat the chicken breast dry with a paper towel and place it on one side of the prepared baking sheet.
In a small bowl, whisk together the olive oil, juice from half a lemon, dried oregano, garlic powder, sea salt, and black pepper.
Brush half of the lemon-herb mixture over the chicken breast, ensuring it is evenly coated on both sides.
Toss the trimmed asparagus spears with the remaining herb mixture and arrange them in a single layer on the other side of the pan.
Roast for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the asparagus is tender and slightly charred.
Let the chicken rest for 5 minutes before slicing to keep it juicy, then serve with the roasted asparagus.