
Yogurt is a fermented dairy product of milk cultured with bacteria — thick and lightly tart.
It gives creamy body with a sour edge, lighter and tangier than cream, which suits lassis and blended fruit drinks. It is already acidic and set on purpose, so citrus will not split it the way it splits cream. Heat will, so keep it out of hot drinks.
Use plain, unsweetened versions. Flavored options carry added sugar.
Greek yogurt
Works if you loosen it. Two parts strained yogurt to one part water or milk stands in for the regular kind.
Kefir
Swaps straight in for shakes and lassis. It gives a thinner, tangier, slightly fizzy drink.
It is dairy and it is alive: keep it cold and go by the date. Whey separating on top is normal and stirs back in; a sharp, yeasty smell means it has gone past tart.