Cook the rice noodles according to package directions until just tender. Drain and rinse under cold water. Set aside.
In a small bowl, whisk together the fish sauce, soy sauce, peanut butter, brown sugar, tamarind paste (or rice vinegar), and Sriracha until smooth. Set aside.
Heat 1 ½ tablespoons of oil in a wok or over medium-high heat. Add the chicken in a single layer and sear for about 3 minutes without stirring.
Flip the chicken pieces and cook for 1 additional minute, or until cooked through.
Immediately add the minced garlic and crushed red pepper flakes. Sauté with the chicken for about 30 seconds, stirring constantly to prevent burning.
Push the chicken mixture to one side of the pan. Add the remaining oil to the empty side, then pour in the beaten eggs. Scramble the eggs, breaking them into small pieces as they cook.
Add the cooked noodles, prepared sauce, bean sprouts, and most of the chopped peanuts to the pan, reserving some peanuts for garnish. Toss thoroughly to combine and heat through.
Remove from heat and garnish with sliced green onions, remaining peanuts, chopped cilantro, and lime wedges. Serve immediately.