I found this on another site and I tried it.
1 cup tamarindo pods, 1 cup sugar, 1/2 tsp. vanilla extract
As with jus de bissap, boil 2 quarts of water. Rinse tamarindo and remove pods if
possible. It is not necessary to remove the seeds. Add to boiling water. Boil for 1-2 minutes. Let stand until cool. Use strainer to remove larger sediment and seeds. Keep in mind that this juice is thick and that you should not remove the pulp. Remove smaller sediment while pouring into container. Add sugar and vanilla to taste. Refrigerate.