The night before place the bowl of your ice cream maker in the freezer to freeze all the way through.
Measure out ½ cup of coconut milk and set aside.
Add remaining coconut milk, sugar, and salt to a small saucepan. Place over medium heat and whisk until sugar is dissolved. Add the vanilla extract.
Stir in the cornstarch to the reserved ½ cup coconut milk until well combined.
Add cornstarch/coconut milk mixture to the saucepan and bring to a boil, stirring frequently.
Boil for 5 minutes, stirring frequently, until the cornstarch is completely cooked and ice cream base has thickened. Transfer to a shallow container, cover, and refrigerate for at least 4 hours.
Add chilled ice cream base to frozen ice cream bowl and churn according to manufacturer's instructions. Churn until it becomes thick and resembles soft serve.
You can serve now or transfer to a pint-size container and store in the freezer until ready to serve. Allow 5-10 minutes to thaw when removing from the freezer.
Serve with toasted coconut, optional