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 the sheet pan, tossing with 0.5 tablespoon of olive oil and a small pinch of sea salt.
Roast the potatoes for 10 minutes to give them a head start since they take longer than the other ingredients.
While the potatoes roast, whisk together the remaining 1 tablespoon of olive oil, lemon juice, dried oregano, and garlic powder in a small bowl.
Carefully remove the pan from the oven and move the potatoes to one side. Place the chicken breast, asparagus spears, and cherry tomatoes on the other side of the pan.
Drizzle the lemon-herb oil mixture evenly over the chicken and vegetables, then season everything with the remaining sea salt and black pepper.
Return the sheet pan to the oven and roast for an additional 15-20 minutes, or until the chicken is cooked through and the asparagus is tender-crisp.
Remove from the oven and garnish with freshly chopped parsley before serving warm.