Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Peel and dice the sweet potato into half-inch cubes, and chop the bell pepper and zucchini into bite-sized pieces.
Place the vegetables on the baking sheet, drizzle with one tablespoon of olive oil, sprinkle with sea salt and black pepper, and toss to coat.
Roast the vegetables in the oven for 20 to 25 minutes until the sweet potatoes are tender and slightly caramelized.
In a small bowl, whisk together the remaining olive oil, tamari, lime juice, chili powder, and garlic powder to create the marinade.
Place the chicken breast in a shallow dish, pour the marinade over it, and let it sit for 10 minutes to absorb the flavors.
Preheat a grill pan over medium-high heat and cook the chicken for 6 to 7 minutes per side until the internal temperature reaches 165°F.
Allow the chicken to rest for 5 minutes before slicing and serving alongside the roasted vegetable medley, garnished with fresh cilantro.