Fill the kettle and boil it. Rinse and finely slice the chilli. Finely grate (or pare) the zest of the lime. Juice it. Crumble the stock cube into a large pan. Stir in 1½ ltrs hot water from the kettle.
Add half the chilli, the lime zest and 1 star anise to the pan with a pinch of salt and pepper. Pop on the lid. Bring to the boil.
Rinse the rice under cold running water. Tip into the pan. Pop the lid back on. Simmer for 20 mins till the rice is almost cooked.
While the rice cooks, rinse and shred the spring green leaves. Rinse the mushrooms. Slice them if they’re large. Rinse half the packet of mung beans. Leave to drain in the sieve. Rinse the mint. Pat dry with kitchen paper. Slice the leaves.
Add the spring greens and mushrooms to the pan. Simmer, without the lid on, for another 5-10 mins till the rice is cooked and the veg are tender.
Stir the lime juice into the soup. Taste and add more salt and pepper if you think it needs it.
Ladle the soup into warm bowls. Top with the mung bean sprouts, the mint leaves and the last of the chilli to serve.