Sago is not a fruit. It is a starch like small pearl use for dessert. You can find it in chinese supermarket normally under the dried section selling in a packet.
I made this tonight and my review is …. It’s not sweet enough. At least 2 more spoons of sugar. Too little sago. More sago needed. This recipe needs work. If not for the sweet mango this have no taste. If you’re going to try this recipe add more sugar and sago.