Preheat your oven to 425°F (220°C) and line a large sheet pan with parchment paper.
Halve the baby potatoes and place them in a bowl with the asparagus spears (ends trimmed).
Pat the chicken breast completely dry with a paper towel to ensure the skin gets maximum crispiness.
In a small ramekin, whisk together the olive oil, dried oregano, garlic powder, sea salt, and black pepper.
Place the chicken on the sheet pan and rub half of the herb oil over the skin and underside.
Toss the potatoes with the remaining herb oil and arrange them cut-side down on the pan around the chicken.
Slice the half-lemon into thin rounds and tuck them under the chicken and among the potatoes.
Roast for 15 minutes, then add the asparagus to the pan, tossing them in the rendered juices.
Continue roasting for another 10-12 minutes until the chicken reaches an internal temperature of 165°F and the skin is golden brown.
Let the chicken rest for 5 minutes before serving to keep the meat juicy.