Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel and dice the sweet potato into 1/2-inch cubes and chop the broccoli into uniform bite-sized florets.
Slice the chicken breast into even 1-inch strips to ensure they cook at the same rate as the vegetables.
In a large mixing bowl, whisk together the extra virgin olive oil, lemon juice, lemon zest, oregano, garlic powder, sea salt, and black pepper.
Add the chicken strips, sweet potato cubes, and broccoli florets to the bowl, tossing thoroughly until every piece is well-coated in the marinade.
Spread the mixture out in a single layer on the prepared baking sheet, making sure not to overcrowd the pan so the vegetables can roast rather than steam.
Place the sheet in the oven and roast for 20-25 minutes, or until the chicken is cooked through and the sweet potatoes are fork-tender and golden brown.
Remove from the oven and serve immediately, finishing with an optional extra squeeze of fresh lemon for brightness.