Clean and wash the beans and cook in boiling salted water for approx. 8-10 minutes until they are firm to the bite. Drain, quench and drain. Peel and finely chop shallots.
Mix the vinegar, mustard, sugar, salt, pepper and oil into a sauce, add the shallots and mix everything with the beans and pomegranate seeds.
Let it steep for at least an hour. Season the salad to taste.
Roast the walnuts in a dry pan, leave to cool. Pour over the salad before serving.