Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Wash and peel the sweet potato, then dice it into uniform 1/2-inch cubes to ensure they cook through at the same rate as the chicken.
Trim the woody ends off the asparagus spears and cut the chicken breast into 1-inch bite-sized pieces.
Place the chicken, sweet potato cubes, and asparagus onto the prepared sheet pan in a single layer.
Drizzle the olive oil and lemon juice over the ingredients, then sprinkle evenly with garlic powder, dried oregano, sea salt, and black pepper.
Use your hands or a spatula to toss everything together until every piece is well-coated with the oil and seasonings.
Spread the mixture out again, ensuring nothing is overcrowded so the vegetables roast rather than steam.
Bake for 20 to 25 minutes, or until the chicken is cooked through and the sweet potatoes are fork-tender and slightly caramelized.
Remove from the oven and serve immediately while the asparagus is vibrant and the chicken is juicy.