In a medium bowl, mix the flour and salt. Make a well in the center.
In a separate small bowl, beat the eggs.
Pour the beaten eggs into the well in the first bowl. With a wooden spoon or spatula, blend the flour into the eggs.
Add the water(s). Sparkling water isn't necessary, but helps make the spaetzle lighter and fluffier.
Mix until the dough begins to pull away from the sides of the bowl. This can take up to 10 minutes, and depending on the size of your eggs, you may need a few tablespoons more flour. The dough should be relatively lump-free, and if you use sparkling water, you should notice small bubbles in it as well.
Let the dough rest 30 minutes. This allows the flour to relax and makes the dough more elastic.
In the meantime, fill a medium pot with water, salt generously (the spaetzle picks up the salt from the water), and bring to a boil.
There are at least three ways to make spaetzle. 1) The traditional method: pour the dough onto a large wooden cutting board. Using a spatula, scrape the dough so it drips off the edge of the board into the boiling water. 2) My preferred method: place a colander or a coarse flat grater over the pot. Scrape some dough into the colander or grater, and force it through with a spatula. 3) The kitchen gadget freak method: Buy a spaetzle maker. Follow the directions in the box.
The trick is to make small batches. The dough will initially sink, then detach from the bottom of the pot and float when it is ready. (Sometimes they need a little help getting away from the bottom of the pot...) As the spaetzle float to the surface, skim them off with a skimmer, slotted spoon, or small sieve.
For one batch, the spaetzle should stay hot if you simply deposit them into a bowl. If you double this recipe, however, you may want to keep the spaetzle warm in the oven while you finish cooking the dough.
Serve hot. If desired, saute with butter. Onions and/or breadcrumbs are also a nice addition.