If you don't like your noodles to be too soft, cook them al dente and take the soup off heat. Serve the soup right away. If you are making the whole batch but know you will have leftovers, take out half (or however much you wish to save) of soup from the pot and set it aside to save. Add just enough noodles for the servings you need at the moment and cook the noodles in the remaining soup in the pot. Save the soup you took out without the noodles. You can cook the noodles in the saved soup when you're ready to have more. It's best to cook the noodles in soup because they will absorb all the flavors, as opposed to making them separately. So, it's easier to take out half the soup and cook it with noodles another time.