Preheat oven 392℉ or 200℃.
In a saucepan combine water, oil, sugar, and salt. Bring to a boil. Then turn off the heat. Add flour and whisk quickly until well combined. Turn on the heat again and cook for one-two minutes more.
Add tapioca flour and whisk until well combined then add the eggs one at a time into the batter. Stir vigorously until uniform and shiny. In the first stirring, the eggs may look separate from the batter, but it will smooth if you keep stirring it.
Transfer choux dough into a pastry bag with a ½-inch plain tip. Line a baking sheet tray with parchment paper then pipe 2-inch balls of choux dough onto a sheet tray. Give a distance of 3 inches in each choux.
Bake on the bottom rack for 10 minutes. After 10 minutes, turn down the temperature to 356℉ or 180℃ then bake for about 30 minutes or until the choux are puffed and golden brown. Remove it from the oven and let the choux cool completely.
Place cold whipping cream in the bowl and whisk until hard peaks. Blender durian with a hand blender until the texture is smooth then combine it to whipped cream and fold it gently until everything is well combined.
Transfer the durian cream into a piping bag. Use a chopstick to pierce the underside of each choux. Fill the chewy choux with durian cream until the choux are full.
Wipe away excess durian cream and do it to the rest of the choux. Chill in the fridge first before serving for the best texture. Enjoy!