Place the noodles in a large bowl. Completely cover them with cold water and soak for 25-35 minutes, until slightly pliable.
In a separate bowl, mix the sauce ingredients together. Set aside. (If adding the peanut butter, it won't completing mix in until heated.)
Generously salt and pepper the chicken pieces. Set a wok or large deep pan over medium heat and add the oil. Sauté the chicken until mostly cooked, 3-5 minutes.
Stir in the garlic, green onions, and bean sprouts. Cook for 1-2 minutes. Push the ingredients to the sides, and scramble the eggs in the middle of pan until firm. Mix together.
Drain the noodles well, then add the noodles and sauce. Stir gently to incorporate, cooking another 3-5 minutes, careful not to overcook the noodles Add 2-4 tablespoons water if needed. Serve warm topped with peanuts and cilantro.
Adding a little peanut butter to the sauce gives the Pad Thai a deeper richer flavor. It is not necessary, but delicious!