Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Wash the sweet potato and cut it 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 baking sheet, keeping them in separate sections.
Drizzle the olive oil over the chicken and vegetables, then squeeze the juice of half a lemon over everything.
In a small bowl, mix the dried oregano, garlic powder, sea salt, and black pepper.
Sprinkle the herb seasoning evenly over the chicken and vegetables, tossing the veggies slightly to coat.
Bake for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender.
Remove from the oven, garnish with freshly chopped parsley, and serve immediately while the chicken is juicy and the vegetables are hot.