1 tsp cumin seeds
2 cups plain yogurt
¾ tsp salt or to taste
½ tsp freshly ground black pepper
Toast cumin seeds in a small skillet over medium heat, stirring continuously, until seeds turn a shade darker and aromatic, about 3 minutes. Let cool and grind in mortar with pestle or in spice grinder until powdery. Set aside.
In a blender, combine yogurt, 2 cups (500mL) cold water and 1 to 2 cups (250 to 500mL) ice cubes. Add salt, pepper and half of the cumin powder and blend until smooth.
Pour into 4 tall glasses to serve. Sprinkle with remaining cumin to garnish.