Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Mince the garlic clove and finely chop the fresh parsley.
In a small mixing bowl, whisk together the olive oil, the juice from the half lemon, minced garlic, dried oregano, chopped parsley, sea salt, and black pepper.
Peel and cut the sweet potato into 1/2-inch cubes and trim the woody ends off the asparagus spears.
Place the chicken breast, sweet potato cubes, and asparagus on the prepared baking sheet.
Drizzle the lemon-herb marinade over the chicken and vegetables, using your hands or a brush to ensure everything is evenly coated.
Bake for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep the meat succulent and juicy.