Soak the tapioca pearls in the 1 cup of non-dairy milk for about an hour.
Transfer soaked tapioca pearls mixture (pearls and any unabsorbed liquid) into a saucepan and add coconut milk, sweetener, vanilla, and salt. Bring contents to a boil on medium heat, stirring occasionally. Reduce heat and simmer for 20 minutes continuing to stir occasionally.
Remove from heat and allow the pudding to cool. Divide it between some glass bowls or jars into portions. If you like it hot, dive in after letting it cool off to an eating temperature (10 minutes). Traditionally it's eaten cold, and that's how I like it, so I chill mine overnight (it makes a lovely breakfast treat by the way!). Prior to eating, stir in the chopped mango (or skip if you're feeling like a traditional plain tapioca pudding only) and enjoy!