Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
In a large bowl, toss the broccoli florets, sliced red bell pepper, and carrots with half of the avocado oil and a pinch of sea salt and black pepper.
Spread the vegetables in a single layer on the prepared baking sheet and roast for 18-20 minutes until they are tender and show light charring.
While the vegetables roast, season the chicken breast evenly on both sides with garlic powder, dried oregano, and the remaining sea salt and black pepper.
Heat the remaining avocado oil in a cast-iron or heavy-bottomed skillet over medium-high heat until shimmering.
Place the chicken in 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 and let it rest for 3-5 minutes to lock in the juices before slicing.
Plate the sliced chicken alongside the roasted vegetables and serve immediately.