Just roughly chop the cucumber after peeling it. In a blender, add them along with fresh squeezed lemon juice, black salt, mint leaves and water. You can add ice cubes as well. Blend it. Strain it. Pour in glasses with crushed ice and jalapeno slices. Serve chilled.
You can also sprinkle chaat masala on top.You can add slit green chillies to the drink if jalapenos are not available.