Step 1Bring lightly salted water to boil in a large soup pot or Dutch oven.
Step 2Meanwhile, stir the flour, salt, eggs and milk together in a large bowl until they form a thick batter, adding more milk if necessary to form a dough. Working in small batches, press the dough through a colander with 1/4-inch holes into the boiling liquid, using a spoon. (Or press through a ricer or spaetzle machine or drop the batter by small teaspoonfuls into the boiling water.) Boil gently, stirring once or twice, until the rivels rise to the surface and are tender, about 5 minutes. Remove with a slotted spoon or drain them in a colander. Repeat with the remaining dough.
Step 3You can toss the hot rivels in melted butter to prevent them from sticking. Or, you can fry them in melted butter until they're golden. Serve plain or dress up with any desired toppings.