Peel the onions and cut them into slices as narrow as possible. Place in a suitable bowl. Boil plenty of water and pour over the onions until boiling hot. Leave for ten minutes.
Then pour off the water and drain the onions on a clean dish. Mix mayo, vinegar, mustard, pepper, salt, paprika and oil to a sauce. Add the onions and mix carefully. Let stand for at least 1/2 hour before serving.
Onion salad goes well with cold roast meat, meat fondue, boiled meat or radette. Arrange on a bed of lettuce as you like.