1. Toast 1 tbsp of the rice in a non-stick frying pan for 4-5 minutes until golden brown, then leave to cool. Roughly crush in a pestle and mortar. Cook the remaining rice in a pan of boiling water according to packet instructions.
2. Heat the oil in a wok or large frying pan and stir-fry the shallots, chilli and lemongrass for 1 minute. Add the pork and stir-fry for 8-10 minutes, until lightly browned and completely cooked through.
3. In a bowl, mix together the lime juice, fish sauce, sugar and 1 tbsp water. Stir into the pork, continuing to cook for 1 minute, then remove from the heat and stir in most of the mint.
4. Separate the lettuce leaves and arrange on plates then, using a slotted spoon, divide the pork between the leaves. Scatter over the crushed toasted rice and reserved mint and serve with steamed rice.