Heat the oven to 190°C/170°C fan/gas 5 and bring a medium saucepan of salted water to the boil. Add the sprouts to the boiling water and cook for 5-6 minutes until tender. Drain, then refresh in a bowl of cold (ideally iced) water.
Drain the sprouts again, then dry them in a clean tea towel. Arrange them on a baking sheet in a single layer. Drizzle with the oil, sprinkle over a pinch of salt then, using the bottom of a bowl or glass, press down on each sprout to smash them fairly flat. Put them in the oven for 20-25 minutes.
Meanwhile, use a pestle and mortar or small food processor to crush the 2 tsp peanuts, chilli and garlic to a paste. Mix in the fish sauce, lime juice, tamarind and palm sugar to make a dressing. Taste and make sure it’s nicely balanced to your taste.
Transfer the cooked, slightly charred and crispy sprouts to a serving platter, then spoon over the dressing. Sprinkle with extra chopped peanuts and serve.
