First, make the roasted rice. Toast the raw rice in a dry frying pan over high heat for 15 minutes, stirring constantly, until golden – it should smell like popcorn. Remove from the pan and let it cool a little before using a mortar and pestle or spice grinder to grind the rice into a powder that resembles fine sand.
Next, bring a saucepan of water to the boil, add the mushrooms and blanch for 20 seconds. Drain immediately and tip into a large salad bowl, then add the rest of the ingredients, including the roasted rice you made earlier.
Toss everything together well and serve right away, garnished with halved baby tomatoes, mint sprigs and lime wedges. This is also refreshing eaten cold, straight from the fridge – but if serving it like this, only add the roasted rice just before serving or it will go soft and you’ll lose that nice contrasting crunchy texture.