If you are able to find sour tamarind pods, break open the brittle pods and remove the moist flesh from the strings that hold them in place. Remove the seeds and use the meat to make tamarind water or juice. For more consistent results in cooking, use "wet tamarind" (makahm bpiak). This is the dark brown flesh of ripe sour tamarind removed from the pods, compressed into compact blocks and sold in markets. Labelled as "wet tamarind" or simply "tamarind," most brands already have the fibrous strings and most of the seeds removed. In buying wet tamarind, squeeze the package to feel its softness; a softer package generally is fresher, more moist, easier to work with and yields better-tasting tamarind juice.



Ingredients:
  • Either fresh tamarind pods or "wet tamarind" (makham bpiak)
  • Warm to hot water
The relative amounts of each are batch variable but ballpark: 1 Tbsp. tamarind pulp to ¼ cup water.

Method:

Making tamarind juice with your fingers works best, and is the most efficient method of dispersing the soft pulp
  1. To use, break a small chunk of wet tamarind and mix with a few tablespoons of water, using your fingers to knead and mush the soft part of the fruit so that it melts into the water.
  2. Gather up the remaining pulp and any seeds with your hand, squeeze out the juice and discard.
  3. You will have produced a fairly thick brownish fluid called "tamarind water". Use this fluid form in your Thai dishes. If you wish to make a large quantity of tamarind water, soaking the tamarind in warm or hot water first to soften will help speed the process.
  4. If you make a large batch of tamarind juice ahead of time, keep it no more than a week in the refrigerator as it may start to ferment after that.

Tip: If the fluid becomes too thick, add a little more water; if the fluid is thin, add more tamarind. For most dishes, you want to have a fluid the consistency of fruit concentrate. If it is too thin and runny, it can dilute flavours and introduce excess liquid to dishes, such as salads, while at the same time, add too little of the desired sour flavour.
The wet tamarind block, when kept airtight in a cool place, lasts indefinitely and needs no refrigeration. It is like preserved dried fruit. Pre-mixed, ready-to-use tamarind water in containers is available from most Southeast Asian markets; however, it may not be as fresh-tasting as making your own and tends to have a very dark color. Once opened, store refrigerated for a couple a couple of weeks only.

Tamarind paste also available online eg importfoods.com