Slice the chicken into small pieces and put in a bowl.
Dissolve the cornstarch in the soy sauce and pour over the chicken. Stir well. Set aside.
To make the Pad Thai sauce, dissolve the tamarind paste in the hot water, then add all other sauce ingredients, stirring to combine and dissolve the sugar.
Separately, soak the noodles in a pot of pre-boiled water until they are nice and soft.
Drain the noodles, and then rinse with cold water.
Heat your wok over medium-high heat.
Add 2 tablespoon of oil plus the garlic. Stir fry until fragrant.
Add the marinated chicken and chicken stock and stir-fry for 5 minutes.
Add the rice noodles to the wok plus the Pad Thai sauce.
Using a couple of utensils, or a pair of tongs, quickly stir-fry the noodles using a tossing motion (like tossing a salad).
Stir-fry 2 minutes.
Mix in the bean sprouts and white pepper,
Continue stir-frying for 2 minutes.
Serve immediately with the chopped peanuts, sliced green onions, coriander, chopped cilantro. Mix these in, and leave some for garnish on top.
Serve with sliced lime.