Preheat your oven to 400°F (200°C).
Halve the baby potatoes and toss them on a large sheet pan with half of the olive oil, sea salt, and black pepper.
Roast the potatoes for 10 minutes to give them a head start.
While potatoes roast, zest and juice the half lemon, and finely mince the garlic cloves.
In a small bowl, combine the remaining olive oil, lemon zest, lemon juice, minced garlic, and dried rosemary.
Remove the sheet pan from the oven, move the potatoes to one side, and place the chicken breast, asparagus, and cherry tomatoes on the pan.
Brush the lemon-herb mixture over the chicken breast and drizzle any remaining over the asparagus and tomatoes.
Return the pan to the oven and roast for 15-20 minutes, or until the chicken reaches an internal temperature of 165°F and the tomatoes have blistered.
Let the chicken rest for 5 minutes before slicing and serving with the roasted vegetables.