In a large pot, heat sesame oil on medium heat. Add garlic, ginger, shallots, and miso paste to the pot. Mix together and sauté for 2 minutes.
Add fish sauce, soy sauce, rice vinegar and mushrooms to the pot and stir well. Allow mushrooms to soften for about 3 minutes.
Pour broth into the pot and bring to a boil. Once boiling, add the chilis and rice noodles and reduce heat to medium. Allow soup to simmer for 8 minutes.
Add the bok choy to simmering soup and cook until the greens are just wilted, about 2 minutes more.
Drop the prawns into simmering broth. 30 seconds after adding the prawns, remove the pot from the heat and serve immediately.
Garnish with beansprouts, fresh cilantro, limes, toasted sesame seeds, green onions and soft boiled egg and enjoy!