Soak the sago in lot of water in a large pan for 15-20 minutes.
Cook till it becomes transparent. This may take at least half an hour depending up on the sago. As soon as it becomes transparent, strain and run it under cold water to avoid it from sticking to each other. Set aside.
In a bowl, scoop out the pulp of avocado. Mash it well without any bites.
Add the condensed milk and milk and mix well.
Now add the sago seeds and mix finally.
Allow to rest in the fridge for an hour.
Sprinkle crushed pistachios on top and serve cold.