Onions peel and roughly chop. Heat the oil in a pot, fry the onions in it until transparent. Add marjoram. Deglaze with broth and add peas. Bring to the boil, cover and simmer over medium heat for about 50 minutes.
Cut salmon into strips. Wash the marjoram, dab dry and pluck the leaves from the stalks. Remove 2 tablespoons of peas from the stock and set aside. Mash the remaining peas in the stock. Add 150 g cream. Season to taste with salt, pepper and sugar. Stir in green peas. Bring the soup to the boil again. Mix in salmon and remaining peas. Whip remaining cream until semi-stiff.
Season to taste with salt, pepper and sugar. Stir in green peas. Bring the soup to the boil again. Mix in salmon and remaining peas. Whip remaining cream until semi-stiff. Arrange the soup in plates, put a blob of cream on each plate and stir a little. Serve garnished with marjoram