1. FOR THE SAUCE: Soak the tamarind paste in the boiling water until softened, about 10 minutes. Push the mixture through a fine-mesh strainer into a bowl, removing the seeds and fibers and extracting as much pulp as possible. Whisk the fish sauce, sugar, 1 tbsp oil, vinegar, and cayenne into the tamarind liquid. (Discard the strained seeds and fibers.)
2. FOR THE NOODLES, SHRIMP, AND GARNISH: Bring 4 quarts water to a boil in a large pot. Off the heat, add the noodles and let stand, stirring occasionally, until softened but not fully cooked, about 10 minutes. Drain the noodles and leave them in the colander.
3. Heat 1-1/2 teaspoons of the oil in a 12-inch nonstick skillet over high heat until just smoking. Add the shrimp and cook, stirring occasionally, until the shrimp are pink, curled, and browned around the edges, about 3 minutes. Transfer to a bowl.
4. Add the remaining 1-1/2 teaspoons oil to the skillet and return to medium heat until shimmering. Add the shallot and garlic and cook until lightly browned, about 1-1/2 minutes. Stir in the eggs and cook, stirring constantly, until scrambled but still moist, about 20 seconds.
5. Add the softened noodles and sauce, increase the heat to heat, and cook, tossing gently, until the noodles are evenly coated, about 1 minute.
6. Add the cooked shrimp, sprouts, and scallions to the skillet and cook, tossing gently, until the shrimp are heated through and the noodles are tender, about 2 minutes. Season with salt to taste and sprinkle with the cilantro and peanuts. Serve with the lime wedges.
Go to full version of