Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Peel the sweet potato and cut into 1-inch cubes, then toss them on the baking sheet with 0.5 tbsp of olive oil, 0.125 tsp salt, and 0.125 tsp pepper.
Roast the sweet potatoes for 15 minutes; meanwhile, trim the woody ends off the asparagus.
Add the asparagus to the baking sheet with the potatoes and roast for an additional 10 minutes until the vegetables are tender.
Season the chicken breast evenly on both sides with the garlic powder and the remaining salt and pepper.
Heat the remaining 0.5 tbsp of olive oil in a heavy-bottomed skillet over medium-high heat.
Sear the chicken for 6 to 7 minutes per side until the internal temperature reaches 165°F and the exterior is beautifully browned.
While the chicken rests for 2 minutes, whisk together the lemon juice, finely chopped parsley, and chopped oregano in a small bowl.
Slice the chicken into strips and serve alongside the roasted vegetables, drizzling the fresh lemon-herb sauce over the meat just before serving.