Put all ingredients together with 1.75 liters of cold water in a large saucepan. Bring to the boil, then simmer on low heat for 20-25 min, skimming occasionally.
Drain the clear soup into a large enough bowl and cool. Keep in refrigerator until ready to use (up to 10 days).
Variation of the basic recipe: If you add vegetables such as carrots, celery and potatoes, respectively, to this Thai clear soup, you will keep a vegetable soup that you can also use for recipes that do not originate in Thailand. All you have to do is chop the vegetables into coarse pieces, put them in a saucepan along with the other ingredients, and simmer gently for 20-25 minutes longer – 40-50 minutes total. Then drain the clear soup as described above and keep.