Cook the rice noodles according to the packet instructions. Meanwhile, make the tamarind sauce. Coarsely grate the palm sugar into a bowl, then add the tamarind paste, 1 tablespoon of fish sauce, a dash of vinegar and 2 tablespoons of boiling water. Mix well so the sugar dissolves, then have a taste and adjust the flavours if needed – it should taste sweet, sour and slightly salty.
Halve, deseed and finely slice the chillies, then place in a bowl with the juice from 1 lime. Drain and toss the noodles in a little sesame oil.
Peel and roughly chop the shallots, then trim and finely slice the chives. Pick and roughly chop most of the mint and basil leaves. Slice the tofu into rough 1cm chunks. Carefully slice through the back of each prawn, scrape out any black bits, then halve lengthways. Rinse the dried shrimps in cold running water, then dry with kitchen paper.
Heat a splash of sesame oil in a large wok over a medium heat, then add the dried shrimps, peanuts and chilli flakes. Cook for 2 to 3 minutes, or until golden. Take the pan off the heat, transfer half of the mixture to a pestle and mortar, then bash until lightly crushed. Set to one side.
Return the remaining shrimps and nuts to a medium-high heat with another splash of sesame oil. Add the shallots and fry for around 2 minutes, or until turning golden. Add the chives, chopped herb leaves, prawns and shredded radish, then cook for a further 2 to 3 minutes, or until the prawns are almost cooked through. Beat and add the egg to the pan, cook for 1 to 2 minutes, then fold through. Add the tofu, noodles, beansprouts and tamarind sauce, then toss well to combine.
Divide the pad Thai between your bowls, sprinkle over the crushed nut mixture and scatter the reserved mint and basil leaves on top. Serve with the pickled chillies and extra lime wedges for squeezing over.