Pad Thai Sauce

Puree the tamarind concentrate using a blender. Add the whole pack + 1 cup of water to make a Tamarind paste.

Rehydrate the dried chilies overnight by soaking them in water to make them soft.
Place the shallots, garlic, and the rehydrated dried chilies in a blender to make a paste.
Heat the oil over medium heat. Stir fry the shallot/garlic/chili paste for a minute to infuse the aroma. Now, you can add 4 cups of water and let it boil.
Once the water is boiling, you can add the palm sugar disc. It may look like a lot of sugar but Pad Thai dish is always sweet, sour, and salty.
You can lower the heat now and add the fish sauce, the salt, and the Tamarind paste. I added around 8 tablespoon of tamarind paste, but you can adjust yours to 6 tbsp; it depends on your taste. Just add the paste gradually and adjust the taste to your liking.
Give the mixture a good stir allowing the palm sugar to dissolve thoroughly.
Try sifting the tamarind paste and use a spoon to dissolve or blend well in the mixture.
This final step is optional; I added the Sriracha sauce to give the sauce a nice color and taste much better.
Once all the ingredients are melted and blended well, transfer the mixture into a glass container. Let them cool down and store them in the fridge for future use.