Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Peel the sweet potato and cut it into half-inch cubes, then trim the tough, woody ends off the asparagus spears.
In a small glass bowl, whisk together the extra virgin olive oil, lemon juice, lemon zest, dried oregano, garlic powder, sea salt, and black pepper.
Place the chicken breast, cubed sweet potatoes, and asparagus on the prepared baking sheet in a single layer without overcrowding.
Drizzle the lemon-herb marinade over the chicken and vegetables, using your hands or a brush to ensure the chicken is well-coated and the vegetables are tossed evenly.
Roast in the center of the oven 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, then serve immediately with the roasted vegetables.