Wash the potatoes and cook them in their skins in boiling water for about 20 minutes. Clean, wash and halve the beans and cook in boiling salted water for 15-20 minutes. Drain potato, peel and press through a potato press. Add oil, vinegar and stock and mix well. Season with thyme, salt and pepper. Drain the beans, rinse with cold water and leave to cool.
Clean, wash and halve the tomatoes. Peel onions and cut into thin rings. Clean, wash and pat dry the picking salad. Pluck into bite-sized pieces. Mix beans, tomatoes, onions and picking salad, arrange on plates. Crumble feta cheese over it, sprinkle with potato vinaigrette