Place the inner pot inside the Instant Pot. Plug it in.
Pour the Vegetable Broth and/or water inside the Instant Pot. Now add all the above mentioned ingredients except the Garnish to the broth.
Place the lid of the instant pot. Set the floating valve to SEALING.
Press the Soup/ Broth Mode. Set it for 20 minutes on Normal Mode & Less Pressure.
When the timer goes off, follow NPR (Natural Pressure Release). Open the Lid. Stir well. Check for Heat, Salt, Sour & Sugar.
Add chili flakes or sriracha or hot chili sauce to make it spicier. You may add a little bit of salt if it is not salty enough for you. Broth and Soy sauce are already salty in nature so be careful when you add salt to the broth. Taste and go from there.
If you think you would like it little sweeter, then go ahead and add a bit more sugar to the broth. For the sour part, tomatoes add to the tartness of the soup. But you will add about 1 tbsp or more of Lime juice to give it adequate sourness.
You see how adaptable this soup is. Adjust your seasonings. Your Tom Yum Soup is ready.