Cut each fresh passionfruit in half and scoop the pulp and seeds into a bowl. Mix with 2 tablespoons of sugar and lemon juice; set aside.

Combine whole milk and half of the heavy cream in a medium saucepan over medium heat, stirring until steaming (5-7 minutes).

Whisk egg yolks and remaining sugar in a separate bowl. Slowly add hot milk mixture to temper yolks, then return to saucepan and cook until thickened (170°F).

Strain custard through a fine-mesh strainer into a bowl to remove lumps, then stir in remaining heavy cream, vanilla extract, salt, and passionfruit mixture.

Cover the bowl and cool to room temperature, then refrigerate for at least 4 hours or overnight.

Pour the chilled mixture into an ice cream maker and churn according to the manufacturer's instructions (about 20-25 minutes).

Transfer churned ice cream to an airtight container, smooth the top, and freeze for at least 2 hours before serving.