Soak 1 tablespoon of tightly packed tamarind in ¼ cup of hot water for 20 minutes, until soft.
Put ½ cup of loosely packed mint leaves in a small blender with the tamarind and its water, 1½ teaspoons of cumin seeds, 1 teaspoon of fennel seeds, and ½ teaspoon of black peppercorns.
Add 1 teaspoon of amchur (dried mango powder) and black salt to taste, and grind to a smooth paste.
Stir the paste into 1½ cups of water. Taste, add more black salt or amchur if needed, and garnish with mint leaves.
