Preheat your oven to 400 degrees Fahrenheit and line a large sheet pan with parchment paper for easy cleanup.
Dice the gold potato into half-inch cubes and cut the chicken breast into bite-sized pieces to ensure they cook quickly and evenly.
In a small bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, dried oregano, sea salt, and black pepper.
Place the potatoes and chicken on the sheet pan, pour the marinade over them, and toss thoroughly to coat every piece.
Spread the mixture into a single layer and roast for 15 minutes.
Remove the pan from the oven, add the trimmed green beans to the empty spaces, and toss them slightly with the pan juices.
Return the pan to the oven and roast for another 10 to 12 minutes until the chicken is cooked through and the potatoes are golden and tender.