Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Slice the sweet potato into thin wedges and trim the tough, woody ends off the asparagus spears.
Place the sweet potato wedges and asparagus on the baking sheet, then toss with 0.5 tbsp of olive oil, 0.125 tsp of sea salt, and 0.125 tsp of black pepper.
Roast the vegetables in the oven for 20-25 minutes, or until the sweet potatoes are tender and the asparagus is lightly charred.
While the vegetables roast, season the chicken breast on both sides with the remaining sea salt, black pepper, and the dried oregano.
Heat the remaining 0.5 tbsp of olive oil in a large stainless steel or cast-iron skillet over medium-high heat.
Add the chicken to the skillet and sear for 6-7 minutes per side, or until the exterior is golden brown and the internal temperature reaches 165°F.
Remove the chicken from the pan to rest; meanwhile, add the minced garlic to the hot skillet for 30 seconds, then deglaze the pan with the juice of the half lemon.
Plate the rested chicken alongside the roasted vegetables and drizzle the fresh lemon-garlic pan sauce over the top before serving.