How do I use tamarind powder?
I would like to point out that the block, pulp, paste and powder each impart different properties to anything you cook or prepare.

The blocks of tamarind pulp are the tamarind fruit pods stripped of the outer husk and compressed tightly together. It is full of fibers and seeds.

The pulp is usually a processed version of the block and should be relative free of fibers and seeds.

The paste is further refined and has been sifted and strained to remove the fibers and seeds.

From what I understand the powder is the dehydrated juice made from the process of compressing the block.

To prepare a container of pulp from a block; break up as much as you need and reconstitute it by covering it with boiled water. 15-20 minutes is sufficient to allow it to soften. Push a bit at a time through a fine meshed strainer. We find that a spatula or small scraper is really helpful for this step. You're essentially rubbing the fibers (and seeds) against the strainer to separate the pulp from the fibers. The pulp falls through and the fibers stay behind.

In the end, you should have a bowl full of soft tamarind paste that is about the consistency of apple sauce. This is now ready to be used and can be stirred directly into your dish.

Save the water that was used to soak the tamarind. You can use it in your cooking in place of some of the water or broth.

How does this paste you made from the block compare with the powder... It doesn't... It seem in my opinion to be a completely different taste. I would not use the powder to prepare pad-thai or a Malaysian curry as it rarely imparts the same punch as freshly prepared pulp.