Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Halve the baby potatoes and place them on one side of the pan, tossing with half of the olive oil, a pinch of sea salt, and black pepper.
Roast the potatoes for 15 minutes to give them a head start on becoming perfectly tender.
While the potatoes are in the oven, whisk together the remaining olive oil, lemon juice, lemon zest, minced garlic, and dried oregano in a small bowl.
Remove the pan from the oven and move the potatoes to one side; place the chicken breast and trimmed asparagus spears in the center.
Drizzle the lemon-herb dressing evenly over the chicken and asparagus, ensuring every piece is well-coated for maximum flavor.
Return the sheet pan to the oven and roast for another 15 to 20 minutes until the chicken reaches an internal temperature of 165°F and the asparagus is vibrant.
Let the chicken rest for 5 minutes before slicing to ensure it stays juicy, then serve alongside the roasted vegetables.