Make the fruit purée. Add the blueberries, banana, and lemon juice to a blender or food processor. Blend until smooth and velvety.
If you prefer an ultra-smooth finish, feel free to strain the purée through a fine mesh sieve to remove the skins and seeds—but this step is totally optional.
Next, combine the base. In a large mixing bowl, stir together the Greek yogurt, sugar, vanilla extract, and milk.
Once combined, pour in the blueberry-banana purée. Mix everything together until the color turns into a dreamy shade of purple.
Then, churn the mixture. Transfer the yogurt mixture into your ice cream maker and churn it according to the manufacturer’s instructions. It typically takes about 20 to 25 minutes to reach that soft-serve consistency.
Finally, serve or store. Enjoy it straight from the machine for a soft and creamy dessert!