Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Slice the baby potatoes into halves or quarters so they are uniform in size.
Place the potatoes on the sheet pan, toss with 0.25 tbsp of olive oil and a pinch of sea salt, then roast for 10 minutes.
While potatoes roast, whisk together the remaining olive oil, lemon zest, lemon juice, minced garlic, oregano, salt, and pepper in a small bowl.
Pat the chicken breast dry with a paper towel and brush both sides with half of the lemon-herb marinade.
Remove the pan from the oven, move the potatoes to one side, and place the chicken and asparagus spears on the other side.
Drizzle the remaining lemon-herb mixture over the asparagus and toss gently to coat.
Return the pan to the oven and roast for another 15-18 minutes, or until the chicken reaches an internal temperature of 165°F and the asparagus is tender.
Let the chicken rest for 5 minutes before slicing to keep it juicy.