Cook half of the potatoes.Peel 1 pound of the potatoes and cut them into chunks. Place them in a pot of salted water and boil until tender. Drain well, mash while warm, and let cool slightly.
Grate the raw potatoes.Peel the remaining 1 pound of raw potatoes and grate them finely or medium-fine. Place the grated potatoes in a clean kitchen towel or cheesecloth and squeeze out as much liquid as possible.
Save the natural potato starch.Let the squeezed potato liquid sit in a bowl for a few minutes. Carefully pour off the liquid and keep the white starch that settles at the bottom. Add this starch back into the dumpling mixture.
Make the dumpling dough.In a large bowl, combine the mashed cooked potatoes, squeezed raw potatoes, reserved potato starch, egg, flour, salt, pepper, nutmeg, and herbs if using. Mix gently until a soft dough forms. If the dough feels too wet or sticky, add a little more flour or potato starch.
Shape the dumplings.With damp or lightly floured hands, shape the dough into round or slightly oval dumplings. Keep them compact so they hold together while cooking.
Cook a test dumpling.Bring a large pot of salted water to a gentle simmer. Cook one small test dumpling first. If it holds together, continue with the remaining dumplings. If it breaks apart, add a little more flour or potato starch to the dough.
Simmer the Hoorische.Carefully lower the dumplings into the simmering water. Do not let the water boil aggressively. Cook for about 12 to 15 minutes, or until the dumplings float to the surface and feel firm but tender.
Drain and serve.Remove the dumplings with a slotted spoon and drain well. Serve hot with bacon gravy, sauerkraut, browned butter and onions, mushroom sauce, or fresh herbs.