Preheat your oven to 400°F (200°C).
On a large baking sheet, toss the broccoli florets, sliced carrots, and bell peppers with 0.5 tablespoon of olive oil, sea salt, and black pepper.
Roast the vegetables for 15 to 20 minutes until they are tender and show slight charring at the edges.
While the vegetables roast, season the chicken breast evenly with garlic powder and a small pinch of salt.
Heat the remaining olive oil in a medium skillet over medium-high heat.
Place the chicken in the skillet and sear for 5 to 7 minutes per side, or until the internal temperature reaches 165°F and the exterior is golden brown.
In a small bowl, whisk together the tamari and sesame oil.
Remove the vegetables from the oven and drizzle them with the tamari-sesame mixture, tossing to coat.
Slice the chicken breast and serve immediately alongside the roasted vegetables and fresh avocado slices.