In a bowl, mix the soy sauce with the peanut butter and half a teaspoon of sugar. Add a little water to achieve a smooth, even consistency, if necessary. Set aside.
Cut the chicken into evenly sized pieces.
Heat a skillet over high heat. Add the chicken pieces and the grated garlic, then cook until golden brown, about 3 to 4 minutes.
Rehydrate or cook the rice noodles according to the package directions. When they are done cooking, reserve a small ladleful of the cooking water, then drain the noodles. Rinse them if necessary to prevent them from sticking together.
Add the drained noodles to the skillet with the chicken. Stir in the bean sprouts, then pour in the sauce. Add a little of the reserved cooking water if necessary to thin out the mixture. Mix thoroughly and continue cooking for 2 to 3 minutes over medium heat.
Divide the chicken pad thai among serving plates or bowls. Sprinkle with fresh cilantro leaves and serve immediately.
