Preheat your oven to 400°F (200°C).
On a large baking sheet, toss the broccoli florets, chopped red bell pepper, and sliced red onion with 1 tablespoon of olive oil, 0.25 teaspoon of sea salt, and 0.25 teaspoon of dried oregano.
Roast the vegetables for 18-20 minutes, tossing halfway through, until they are tender and have developed a slight char.
While the vegetables roast, season the chicken breast evenly on both sides with the garlic powder, remaining 0.25 teaspoon of sea salt, black pepper, and remaining 0.25 teaspoon of dried oregano.
Heat the remaining 0.5 tablespoon of olive oil in a medium skillet over medium-high heat.
Place the chicken in the skillet and sear for 6-7 minutes per side, or until the internal temperature reaches 165°F and the exterior is golden brown.
Allow the chicken to rest for 3 minutes before slicing and serving alongside the roasted vegetables.