Boil up broth in a wok. Cook the green beans and broad beans in it for 15 minutes. Rinse lentils cold and add them to the beans ten minutes before the end of the cooking time. In the meantime, peel, wash and dice the potatoes. Remove vegetables and stock from the wok. Heat the oil in the wok. Fry the diced potatoes for eight minutes, turning.
Season with salt. Add bean and lentil vegetables and heat briefly. Remove the marjoram leaves from the stalks, except for something to garnish. Add to vegetables. Season to taste with vinegar, salt and pepper. Serve garnished with marjoram