How do I keep egg noodles from sticking together for later use?

I recommend cooking the noodles and draining them in small batches (like little nests). The noodles will separate out when you add them to the hot soup. I've never heard of any method other than tossing in oil or butter to keep noodles from sticking together. We have this problem with Vietnamese noodle bowls. So my mother's solution was to take the drained but still wet noodles, and make little bundles or nests, , overlapping slightly,which she put on a tray. When it can time to make a noodle bowl, simply peel off a bundle or two, add toppings and dressing, then toss everything together. The liquid in the dressing will lubricate the noodles and they separate out easily. You can do something similar with the noodles for the soup. Rinsing out the starch is not going to keep the noodles from clumping together.

If you're talking about fresh noodles, they'll dry out enough not to stick pretty fast (depending on the room)- just make sure to shuffle them a bit from time to time while drying.

Toss them with some butter or oil.