Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Halve the baby potatoes and trim the tough, woody ends from the asparagus spears.
Place the chicken breast and halved potatoes on the sheet pan, drizzling with the extra virgin olive oil and seasoning with the ground sumac, sea salt, and black pepper.
Roast the chicken and potatoes for 15 minutes.
Carefully remove the pan from the oven, slide the chicken and potatoes to one side, and add the asparagus spears to the empty space, tossing them slightly in any remaining oil on the pan.
Return the pan to the oven and roast for an additional 10-12 minutes, or until the chicken reaches an internal temperature of 165°F and the potatoes are golden.
While the chicken rests, finely mince the garlic and parsley, then whisk them together with the lemon zest and lemon juice in a small bowl to create the gremolata.
Spoon the fresh gremolata over the roasted chicken and vegetables immediately before serving.