Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper.
Wash and peel the sweet potato, then cut it into 1-inch cubes. Trim the woody ends off the asparagus.
In a small bowl, mince the garlic and combine it with the dried rosemary, dried thyme, sea salt, and black pepper.
Pat the chicken breast dry with a paper towel. Rub it with half of the olive oil and half of the herb-garlic mixture.
Place the sweet potato cubes on the sheet pan, toss with the remaining olive oil and herb mixture, and move them to one side. Place the chicken breast in the center.
Roast for 15 minutes. Remove the pan and add the asparagus and cherry tomatoes to the remaining open space.
Return the pan to the oven and roast for another 10-12 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are tender.
Squeeze the fresh lemon juice over the chicken and vegetables just before serving for a bright, zesty finish.