Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Wash and dice the sweet potato into 1/2-inch cubes and trim the woody ends off the asparagus spears.
Pat the chicken breast completely dry with paper towels to ensure the surface gets crispy during roasting.
In a small bowl, whisk together the olive oil, minced garlic, chopped rosemary, and chopped thyme.
Place the chicken, sweet potatoes, and asparagus on the prepared baking sheet in a single layer.
Drizzle the herb oil mixture over the chicken and vegetables, then season everything with sea salt and black pepper.
Squeeze the juice from the half lemon over the tray and place the squeezed lemon hull on the sheet for extra aroma.
Roast 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 ensure it stays juicy.