Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Place the broccoli florets, bell pepper strips, and red onion wedges on the baking sheet.
Drizzle the vegetables with half of the olive oil and season with half of the sea salt and black pepper; toss to coat evenly.
Roast the vegetables in the oven for 18-20 minutes until tender and slightly charred at the edges.
While vegetables roast, season the chicken breast on both sides with the remaining sea salt, black pepper, dried oregano, and garlic powder.
Heat the remaining olive oil in a medium skillet over medium-high heat.
Place the chicken in the skillet and sear for 5-7 minutes per side, or until the internal temperature reaches 165°F.
Remove the chicken from the pan and let it rest for 3 minutes before slicing.
Plate the roasted vegetables alongside the chicken and drizzle everything with fresh lemon juice before serving.