Preheat your oven to 425°F (220°C) and line a large baking sheet with parchment paper.
Cube the sweet potato into 1/2-inch pieces and trim the tough, woody ends off the asparagus spears.
In a small mixing bowl, whisk together the olive oil, lemon zest, lemon juice, minced garlic, oregano, thyme, sea salt, and black pepper.
Place the chicken thighs, sweet potato cubes, and asparagus on the prepared baking sheet.
Drizzle the lemon-herb mixture over the chicken and vegetables, tossing thoroughly with your hands or tongs to ensure everything is evenly coated.
Spread the ingredients out into a single layer, making sure the chicken thighs are not crowded so they can crisp up properly.
Bake for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender.
Optional: Turn the oven to broil for the last 2 minutes of cooking to achieve a deeper golden-brown finish on the chicken.