2) Combine the broth, soy sauce, and fish sauce, if using, to the saucepan and bring to a simmer.
3) Add the remaining ingredients except the mangetout, spring onions, and sesame oil. Simmer for 20 mins, and then add the mangetout.
4) Cook for just a few mins longer, until the mangetout have softened but are still bright green. Add the spring onions to the saucepan, remove from heat, and ladle into serving bowls.
5) Drizzle a bit of sesame oil over the top of each serving.