Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch bite-sized pieces and chop the broccoli into small, uniform florets.
In a large mixing bowl, whisk together the extra virgin olive oil, minced garlic, lemon juice, lemon zest, dried oregano, sea salt, and black pepper.
Add the chicken pieces and broccoli florets to the bowl, tossing thoroughly until every piece is evenly coated in the lemon-herb marinade.
Spread the chicken and broccoli in a single layer on the prepared baking sheet, ensuring there is enough space between pieces to allow for roasting rather than steaming.
Roast in the center of the oven for 15-18 minutes until the chicken is cooked through and the broccoli edges are slightly charred and golden.
While the chicken roasts, ensure your pre-cooked brown rice is warmed through.
Divide the warm brown rice into a bowl and top with the roasted lemon chicken and broccoli, drizzling any remaining juices from the pan over the top.