How to Make It
In a large bowl, cover the noodles with cold water and let stand for 2 hours. Drain well.
Preheat the oven to 375°. Spread the peanuts on a baking sheet and toast for 10 minutes, until fragrant. Let cool, then coarsely chop.
Meanwhile, in a medium saucepan, combine the tamarind concentrate, fish sauce, palm sugar, vinegar, shrimp paste and chile powder and bring to a boil, stirring to dissolve the sugar. Let cool.
In a large nonstick skillet, heat 1 tablespoon of the canola oil. Add the dried shrimp and stir-fry over high heat for 1 minute. Using a slotted spoon, transfer the shrimp to a paper towel–lined plate. Let cool slightly, then coarsely chop the dried shrimp.
In the same skillet, cook the fresh shrimp over moderately high heat, turning once, until just white throughout, about 2 minutes. Transfer the shrimp to a plate.
Add the remaining 2 tablespoons of canola oil to the skillet and heat until shimmering. Add the tofu, garlic, shallot and preserved radish and stir-fry over high heat, until the garlic and shallot are golden, about 1 minute. Add the noodles and 3 tablespoons of the tamarind sauce and stir-fry until the noodles are coated and most of the sauce is absorbed, about 2 minutes. Add the egg and chives and cook, stirring and tossing, until the egg is cooked, about 1 minute. Remove the skillet from the heat and stir in the peanuts and dried shrimp. Transfer to a plate, top with the head-on shrimp and garnish with the bean sprouts and lime wedges. Save the remaining tamarind sauce for subsequent batches.
The tamarind concentrate, palm sugar, shrimp paste, chile powder, dried shrimp and preserved sweet radish (also sold as sweet-salty turnip) are available at specialty food stores and at templeofthai.com.