Soak the rice noodles in warm (not hot) water for 25-30 minutes until pliable but still firm. Drain well.
Whisk the tamarind paste, palm sugar, fish sauce, and water in a small bowl until the sugar dissolves. Taste and adjust the sweet-sour-salty balance.
Heat 1 tablespoon oil in a large wok over high heat. Sear the shrimp 1-2 minutes per side until pink and just opaque; remove to a plate.
Add the remaining oil to the wok. Cook the garlic 15 seconds, then add the beaten eggs and scramble into ribbons.
Add the drained noodles and sauce; toss 3-4 minutes until glossy and tender, adding a splash of water if they look dry.
Add bean sprouts, chives, and chili flakes; toss 1 minute. Return the shrimp and toss 30 seconds to warm through.
Serve immediately topped with crushed peanuts, with lime wedges, extra bean sprouts, and chili flakes on the side.