Preheat an oven to 425 degrees Fahrenheit with an empty baking sheet on the middle rack. Toss the halved potatoes in two tablespoons of the olive oil until thoroughly coated, then carefully place them on the preheated baking sheet in the oven. Roast the potatoes for approximately 20 minutes (or longer if needed), turning the potatoes once during cooking. Remove the potatoes from the oven and allow them to cool to room temperature.
Cook the beans al dente in plenty of boiling water, drain them and cool them under cold running water and drain them again thoroughly. Combine the beans in a large bowl along with the roast potatoes, the remaining 2 tablespoons olive oil, garlic, chives, parsley, basil, oregano, lemon, salt and pepper. Toss the salad until well combined and let stand at room temperature for 20 minutes before serving.