I modified this from recipes I found online. It’s one of those things that doesn’t actually require cooking, it just requires dumping everything in a blender. And it’s way easier on my system (particularly whichever spot my gallbladder used to be) than the full-fat variety (that often even has cream in it in addition to yogurt):

1 cup of water
3 to 4 cups of low-fat or non-fat plain yogurt (I have had trouble measuring it, but it’s somewhere in there)
1/3 cup of sugar
1/2 teaspoon of salt
1 teaspoon of rosewater
However much fruit you want (I’ve been adding a half a peach or a whole peach, but it can be any kind of fruit and any amount that tastes good)

Stick it all in blender. Blend it until everything’s blended in smoothly and it’s frothy on top. Then pour it out and drink it. (I got the fruit idea because I’ve had mango lassi, but there aren’t any mangoes around at the moment, so I figured any fruit would work.)