Heat a deep frying pan or small pot over medium low heat adding all ingredients except the chili powder.
Cook the sauce until the palm sugar and regular white granulated sugar have dissolved. Taste the sauce at this point and add a little more sugar if too sour. The end result should be a well balance sweet/sour flavor.
To make it more spicy, add in the optional Thai chili flakes or chili powder to taste.
Remove from heat, allow to cool and store in a jar until needed for the main dish.
For the Pad Thai:
Note: Soak the dried or fresh rice noodles in cold water for up to a day in advance. If you boil a pot of water while cooking the Pad Thai, you can quickly dip the noodles you're going to use with a small strainer and watch them "melt" and become translucent. This only takes a few seconds; quickly drain and throw them in the wok when you get to that step.
Heat up a wok and add oil. When the oil is near its smoke point, add the minced garlic and do a few quick stirs. Add chicken and shrimp into the wok stirring until half-cooked, then add the tofu pieces (if using). Add the eggs, stirring about to do a scramble of sorts.
Dip, drain and stir in the noodles at this point. Add enough of the Pad Thai sauce to your taste. add the bean sprouts and chives shortly before removing from heat.
Serve with some peanuts sprinkled on top, fresh bean sprouts and lime wedges. Garnish with cilantro.