Mix together 1 part tamarind liquid (directions below) and 3 parts sparkling water or orange juice. Add sugar to taste and pour into a glass over ice.
If using fresh tamarind, break off and discard pods (some bits will stick).
Put the sticky brown paste with seeds (or all or part of a brick of tamarind paste, which often has seeds too) in a bowl and add about 3 parts hot water to 1 part paste. Let stand 3 to 4 minutes to cool. Squeeze pulp from seeds.
Rub tamarind mixture through a fine strainer into a bowl; discard residue. Use liquid, or freeze to store.
Nutritional analysis per cup with 2 teaspoons sugar.