Add the potatoes to a 9x13 inch baking dish. Toss them with the olive oil, lemon juice, salt and black pepper, making sure they are all evenly coated. Bake the potatoes for 20-25 minutes or until they’re starting to look brown.
Carefully remove the baking dish from the oven and stir through the green beans and tired oregano. Return to the oven and finish roasting for about 15 minutes, or until the potatoes are golden and the green beans are tender.
Just before serving, toss the roasted potatoes and beans with the chopped mint, lemon zest and feta cheese.