Preheat your oven to 400°F.
Peel and dice the sweet potato into half-inch cubes and chop the red bell pepper into bite-sized pieces.
Toss the sweet potato, bell pepper, and broccoli florets with half of the olive oil, 0.25 tsp sea salt, and 0.125 tsp black pepper on a large parchment-lined baking sheet.
Roast the vegetables for 20 to 25 minutes, tossing halfway through, until the sweet potatoes are tender and the edges are slightly caramelized.
While the vegetables roast, season the chicken breast on both sides with garlic powder, dried oregano, and the remaining sea salt and black pepper.
Heat the remaining olive oil in a large skillet over medium-high heat.
Place the chicken in the skillet and sear for 6 to 7 minutes per side until the exterior is golden brown and the internal temperature reaches 165°F.
Remove the chicken from the heat and let it rest for 5 minutes to keep the juices locked in before slicing.
Plate the sliced chicken alongside the roasted vegetables and finish with a fresh squeeze of lemon juice for brightness.