Prepare all the ingredients. Cut the king oyster mushrooms into pieces. Rinse the shrimp, leaving the shells on. Cut the lemongrass into sections. Slice the beef thinly.

Bring enough water to a boil for about 5 bowls of soup. Add the lemongrass and chopped pineapple, then bring to a boil. Stir in the Thai hot pot seasoning and Tom Yum paste, along with 2 tablespoons sugar and 2 tablespoons fish sauce, adjusting to taste. Add the shrimp and cook until done, then remove and set aside. Next, add the mixed seafood, cook briefly, then remove and set aside. Finally, add the king oyster mushrooms and leave them in the broth.

Arrange each ingredient on separate plates. Thinly slice the napa cabbage and sawtooth herb (culantro) and place on a serving dish. To serve, put rice vermicelli noodles in a bowl, top with shrimp, beef, and seafood, then ladle the hot broth over. Serve hot with vegetables and culantro. This spicy noodle soup is perfect for a cold day!