Boil 400 grams potatoes in the salted water until done, drain and mash into a puree. Grate finely remaining potatoes, squeeze very carefully dry with paper towel, mix with mashed potatoes, season with salt, pepper and nutmeg. If the mixture is too liquid, add the starch. If it's too thick-milk. Form dumplings and boil them in salted water on low heat for 20 minutes.