Preheat your oven to 400°F and line two large sheet pans with parchment paper for easy cleanup.
In a small bowl, whisk together the olive oil, the juice of one lemon, minced garlic, sea salt, black pepper, and dried oregano.
Cut the chicken breasts into 1-inch bite-sized pieces and slice the red bell peppers into strips.
Place the chicken pieces on one half of the sheet pans and arrange the broccoli florets and bell pepper strips on the other half.
Drizzle the lemon-garlic marinade over the chicken and vegetables, tossing them gently to ensure everything is evenly coated.
Thinly slice the second lemon and place the rounds over the chicken and vegetables for extra flavor and moisture.
Roast in the oven for 20-25 minutes until the chicken is cooked through and the vegetables are tender with slightly charred edges.
While the chicken is roasting, combine the dry white rice and water in a medium pot, bring to a boil, then cover and simmer on low for 15 minutes.
Fluff the rice with a fork and serve it in bowls topped with the roasted lemon chicken and vegetables.