Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Chop the broccoli florets, red bell pepper, and carrots into uniform, bite-sized pieces to ensure even roasting.
Place the vegetables on the baking sheet, drizzle with half of the avocado oil, and season with a pinch of sea salt and black pepper.
Roast the vegetables in the oven for 15-20 minutes until they are tender and show slight charred edges.
While the vegetables roast, season the chicken breast evenly on both sides with garlic powder, onion powder, smoked paprika, and the remaining salt and pepper.
Heat the remaining avocado oil in a cast-iron or heavy-bottomed skillet over medium-high heat.
Place the chicken in the hot skillet and sear for 6-7 minutes per side until the exterior is golden brown and the internal temperature reaches 165°F.
Remove the chicken from the pan and let it rest for 5 minutes to lock in the juices before slicing.
Arrange the sliced chicken on a plate with the roasted vegetables and drizzle everything with fresh lemon juice before serving.