Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Toss the cubed sweet potatoes, broccoli florets, and sliced bell peppers on the baking sheet with half of the olive oil, a pinch of sea salt, and black pepper.
Spread the vegetables in a single layer and roast for 20-25 minutes until the sweet potatoes are tender and the broccoli edges are slightly charred.
While the vegetables roast, season both sides of the chicken breast with garlic powder, dried oregano, and the remaining sea salt and pepper.
Heat the remaining olive oil in a stainless steel or cast-iron skillet over medium-high heat until shimmering.
Place the chicken in the skillet and sear for 6-7 minutes per side, or until the internal temperature reaches 165°F and the crust is golden-brown.
Remove the chicken from the pan and let it rest on a cutting board for 5 minutes to ensure the juices redistribute.
Slice the chicken and serve alongside the roasted vegetables, finishing the entire plate with a fresh squeeze of lemon juice for brightness.