Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Wash and dice the Yukon Gold potato into 1-inch cubes, leaving the skin on for extra fiber.
In a small bowl, toss the potato cubes with 0.5 tablespoons of olive oil, half of the sea salt, and half of the black pepper.
Spread the potatoes in a single layer on the baking sheet and roast for 12 minutes.
While the potatoes are roasting, rub the chicken breast with the remaining olive oil, dried oregano, garlic powder, and the rest of the salt and pepper.
Remove the baking sheet from the oven, move the potatoes to one side, and place the chicken breast and trimmed green beans on the other side.
Return the pan to the oven and roast for an additional 18 to 20 minutes, or until the chicken reaches an internal temperature of 165°F.
Remove from the oven, drizzle the fresh lemon juice over the chicken and vegetables, and garnish with chopped fresh parsley before serving.