Salted pickled radish adds a flavour that’s pretty hard to put your finger on, but really adds to the complexity of the dish. Ask for it at your Asian grocer.
For the tamarind sauce, blend the chillies and shallots with 2 tablespoons of water until a smooth paste. Add the chilli paste to a small saucepan over medium heat and cook for 1-2 minutes until it mostly dries out. Add the tamarind concentrate, palm sugar, fish sauce and 150 ml of water and cook for 4-5 minutes, or until it has a thick and saucy consistency. Take off the heat.
Heat a wok until very hot, add half the oil and heat until starting to shimmer. Add the egg and stir through as it fries. Remove from the wok and drain on paper towel.
Add the remaining oil to the wok and heat through. Add the tofu and stir-fry until it starts to brown. Add the dried shrimp and radish and quickly stir through. Add the prawns and stir-fry for 2 minutes. Loosen the noodles with your fingers and add to the wok with about 150 ml of water. Stir through gently so as not to break the noodles up. Cook for 2 minutes. Add half of the tamarind sauce, the beansprouts, egg and half of the peanuts and stir through. Cook for 30 seconds and then stir in the garlic chives.
Serve immediately, garnished with coriander and the remaining peanuts, and with the chilli in rice vinegar on the side (if using). The leftover tamarind sauce will keep for a couple of weeks in the fridge.