Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Scrub the sweet potato and pierce it several times with a fork. Place it on the baking sheet and roast for 40-45 minutes until soft and tender.
Trim the woody ends off the asparagus. In a bowl, toss the spears with 0.5 tbsp of olive oil, minced garlic, and a pinch of the sea salt and black pepper.
Add the asparagus to the oven on a separate tray during the last 12-15 minutes of the sweet potato's roasting time.
While the vegetables roast, season the chicken breast evenly on both sides with the remaining sea salt, black pepper, and dried oregano.
Heat the remaining 0.5 tbsp of olive oil in a heavy-bottomed skillet over medium-high heat.
Place the chicken in the pan and sear for 6-7 minutes per side, ensuring a deep golden crust forms and the internal temperature reaches 165°F.
Remove the chicken from the heat and let it rest for 3 minutes to lock in the juices.
Slice the sweet potato open and plate it alongside the chicken and roasted asparagus, finishing everything with a bright squeeze of fresh lemon juice.