I substituted everyday ingredients for Thai ingredients as follows:
Lemongrass + galangal + kaffir lime leaves can be swapped for ginger
You can change condensed milk to milk
Thai chili oil can be swapped for gochujang and ra-yu chili sesame oil
It's easy and delicious, and even people who aren't fond of Thai herbs will love this.

Even if you don't have the usual Thai herbs that are in tom yum goong soup, as long as you add lots of sliced ginger, the flavor is fairly close to the real thing.
If the heat is too high when you simmer the soup, the milk will separate, so cook over medium-high heat. In order to cook everything efficiently, have all the ingredients prepared beforehand. Recipe by Ikumihan