Ingredients

• 1/2 pound tamarind from a pliable block
• 7 cups water, divided
• Ginger syrup
• 1/4 teaspoon kosher salt
• 1 (1-liter) bottle soda water or seltzer, chilled

Instructions

1. Break up tamarind with your fingers into a small heavy saucepan. Add 2 cups water and simmer, stirring occasionally and breaking up tamarind as it softens, 20 minutes. Remove from heat and let stand 15 minutes. Strain through sieve into a bowl, pressing on and then discarding solids.
2. Whisk together ginger syrup, tamarind purée, remaining 5 cups water, and kosher salt in a large pitcher. Chill until cold.
3. Stir drink (it will separate as it stands), then pour into glasses filled two-thirds with ice. Top off with soda water.