Crush the lemongrass to release the oil and aroma. I usually just do this by pounding on it using the dull end of a cleaver or a pestle. Slice the stalks into 3-4 inch pieces.Crush the garlic as well and then peel. Break apart the kaffir limes and slice the chillies.
For the veggies, I simply sliced the straw mushrooms in half and the baby corn into small pieces. If using oyster mushrooms, simply break these apart.
Heat a large pot over medium high heat. I used a dutch oven.
Add in the oil. Once hot, sauté the onion and tomatoes. Add in the garlic, lemongrass, kaffir lime leaves, chiles, galangal or ginger with pepper. Sauté the aromatics for 2 to 3 minutes over medium high heat until the onion is translucent.
Add in the vegetable broth to the pot.
Cover the pot and leave to boil over high heat. Leave for the aromatics to release their flavours.
Once the soup boils and is fragrant, add in the mushrooms, baby corn, tomatoes, sugar, fish sauce, and salt, to taste. Mix well and then leave to simmer of medium high heat for 5 minutes or until the mushrooms and corn cook down.
Mix in the lime juice, evaporated/coconut milk (if making the creamy version), and chili sauce. Mix everything together and taste the soup. Feel free to add more lime juice (for sourness), sugar (for sweetness), chili sauce (for spice) and fish sauce (for saltiness). You can also add in more salt as needed.
Leave the soup to cook down for another 7 to 8 minutes over medium heat for all the flavours to infuse. At this point the tomatoes will have cooked down.
Kaffir lime leaves and lemongrass are tough and not meant to be consumed. You can remove the aromatics from the soup or simply set these aside when you come across them in your soup.
Serve the soup hot with more lime juice and some cilantro, if desired. Enjoy!
To make a tom yum noodle soup, soak thin rice noodles in boiling hot water for 7-8 minutes or until the noodles turn into a solid white colour and are chewy to your liking.
Once chewy to your liking, drain the noodles from the water.
Transfer the noodles to a bowl.
Pour tom yum soup over the noodles and top with some vegan 'fish' and 'shrimp' balls or other toppings of your choice (like fried beancurd). Garnish with cilantro, if desired. Enjoy!