That said, this recipe is only an experiment. The result was delicious. However, there are probably better and/or easier ways to make tamarind ice cream. For example, tamarind syrup (which I couldn't find in stores but is available on the internet) could make things much easier because then you could formulate a recipe without the tamarind mash that I made from tamarind pulp. But here's what I did. (General Guidelines and Advice found here.)
Tamarind Ice Cream
1/2 c. + 2 T tamarind mash (see recipe below)
2 c. soy creamer (note: this would also be really good with coconut milk too!)
1 1/2 c. soy milk
1 c. sugar
2 T. arrowroot
1 t. vanilla
Mix ¼ cup of soy milk with the 2 tablespoons of arrowroot and set aside.
Combine tamarind mash with soy creamer in a sauce pan. Whisk together over medium heat. If, like I did, you find that your tamarind mash has some fibrous bits floating around in the liquid, pour the mixture through a strainer to remove those tough pieces. Return the liquid to the sauce pan.
Add the remaining soy milk and sugar. Raise the heat and bring the mixture to a boil. When the mixture has just started to boil, take off the heat and immediately stir in the arrowroot slurry. This should immediately cause the liquid to thicken (not a lot, but a noticeable amount; it will be thicker when it cools).
Add the vanilla.
Set the ice cream mixture aside to cool. Freeze according to your ice cream maker's instructions.
1/2 c. seedless tamarind pulp*
1/4 c. sugar
1 1/2 T. lime juice
1 c. + 2 T. water
Combine the tamarind pulp, sugar, lime, and 1/4 cup water in a sauce pan. Heat to dissolve the sugar. Stir in about 1/4 cup water at a time; this will make mixing easier. After all the water is mixed in, transfer the mash to a blender and puree (be careful with the steam!).
This makes about 1 1/4 cups of tamarind mash, more than you'll need for the above ice cream recipe. You can save the rest of the mash and mix it with water and sugar for aqua de tamarindo!
* I bought a package of seedless tamarind pulp at a local Indian grocery store. You could also buy tamarind pods and scrape out the pulp and remove the seeds. Indian, Thai, or Hispanic stores are good places to find tamarinds.