Even now in modern India, many people keep livestock for milk. Milking takes place very early each morning. Towards the end of the day, the milk that remains after the day's requirements is boiled, cooled, and poured into large clay urns which are left overnight to produce yoghurt for the following day.
The important task of churning the yoghurt to make butter (makhan) is undertaken with great enthusiasm at the crack of dawn. Some of the makhan is eaten as it is with yoghurt and breads and the rest is heated and clarified to make ghee. The liquid that is left after churning the yoghurt and removing the makhan is the lassi.
Lassi is a refreshing and nutritious drink that is served throughout the heat of the day and also with meals instead of water.
I do not expect you to go through this lengthy process in order to enjoy home made lassi, so you will find the following method quick, simple, and perfectly acceptable.
