In the city of Aden, in Yemen, we were used to going out to have this drink on a warm summer day with family. This is often served in the states in some South Asian [Indian], and Turkish restaurants. Indians call it Lassi, and the Turkish call it Ayran. Some Middle Eastern stores sell it salty with mint. I personally used to like it with salt, but it is originally made with sugar in Yemen. I am going to give you the recipe with sugar, since the salt is just my personal preference. My husband thinks I am weird to like it with salt.
To serve two you will need:
1) 2 cups of plain yoghurt
2) 1/4 cup of sugar–more if you like it sweeter
3) 2 cups of cold water–if you like it thinner you can use 3 cups
4) 1 cup of ice
Place all the ingredients in a blender and blend well. Serve cold.