Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Wash and halve the baby potatoes, and trim the tough, woody ends off the asparagus spears.
In a small mixing bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, dried oregano, sea salt, and black pepper to create the marinade.
Place the chicken breast, halved potatoes, and trimmed asparagus onto the prepared sheet pan in a single layer.
Drizzle the lemon-herb marinade over the chicken and vegetables, using your hands or a brush to ensure everything is evenly coated.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the potatoes are fork-tender.
Let the chicken rest for 5 minutes before slicing to keep it juicy, then serve alongside the roasted vegetables.