Dry roast cumin seeds and peppercorns in a non-stick pan till fragrant. Switch off the heat and cool down to room temperature.
Roughly tear mint leaves and put in a mixer jar. Add salt, black salt, lemon juice, 3-4 tbsps water and 1 tbsp roasted ingredients and grind to a smooth paste. Store the remaining roasted ingredients in an airtight container for future use.
Pour the prepared paste into a bowl of ice cubes. Add 3 cups of water and mix well.
Grind dates with ΒΌ cup water to a smooth paste and add to the same bowl and mix well.
Pour the date jaljeera into 4 individual serving glasses and serve chilled.