Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Halve the baby potatoes and place them on one side of the baking sheet, tossing with 0.5 tablespoon of olive oil and a pinch of sea salt.
Roast the potatoes for 10 minutes to give them a head start.
While potatoes roast, pat the chicken breast dry with a paper towel and season both sides with the dried oregano, garlic powder, sea salt, and black pepper.
Remove the baking sheet from the oven, move the potatoes to one side, and place the chicken breast in the center.
Arrange the trimmed asparagus on the remaining side of the sheet and drizzle the chicken and asparagus with the remaining 0.5 tablespoon of olive oil.
Squeeze the juice from the lemon over the chicken and asparagus, then place a few thin lemon slices directly on top of the chicken.
Return the sheet to the oven and roast for 15-20 minutes, or until the chicken reaches an internal temperature of 165°F and the asparagus is tender-crisp.
Let the chicken rest for 5 minutes before slicing and serving alongside the roasted potatoes and asparagus.