Rinse the potatoes and boil for 20-25 minutes in salt water.
Peel and dice the onion. Bring the broth to a boil. Add the onions and saute for about 5 minutes until translucent. Drain the potatoes and cut into slices. Pour in the broth and let soak for about 30 minutes.
Rinse the green beans and cut into pieces. Bring the salt water for a boil and blanch the green beans for 8-10 minutes. Rinse the pickled herring, pat dry and cut into pieces. Rinse the radishes, chop of the stalks and cut into small pieces.
Mix the vinegar, mustard, sugar and oil. Season with salt and pepper. Drain the green beans, rinse in cold water and drain well. Mix the potatoes with the dressing. Fold in the green beans, pickled herring and radishes. Arrange the potato salad on lettuce and serve.