Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Pat the chicken breast completely dry with a paper towel to ensure the skin gets crispy.
In a small bowl, combine half of the olive oil with the sea salt, black pepper, garlic powder, and dried oregano.
Rub the herb mixture evenly over both sides of the chicken breast and place it on one side of the prepared baking sheet.
Trim the woody ends off the asparagus and toss the spears with the remaining olive oil and a pinch of salt.
Roast the chicken for 10 minutes, then add the asparagus to the other side of the tray and roast for an additional 12 minutes.
Check that the chicken has reached an internal temperature of 165°F and the asparagus is tender.
Remove from the oven, squeeze fresh lemon juice over the chicken and vegetables, and top with fresh parsley and avocado slices before serving.