Step 1: Prepare the Strawberry Puree : In a saucepan, combine chopped strawberries, sugar, and lemon juice. Cook over medium heat for about 10 minutes, stirring occasionally, until the berries soften and release their juices. Mash lightly or blend into a purée using a blender or immersion blender. Stir in vanilla extract, then cool completely in the refrigerator.

Step 2: Make the Custard Base : In a medium saucepan, heat the milk, cream, and half of the sugar until warm but not boiling. In a separate bowl, whisk egg yolks with the remaining sugar until pale and creamy. Slowly add some of the warm milk mixture into the yolks while whisking constantly (to temper the eggs). Pour everything back into the saucepan and cook on low heat, stirring constantly, until the mixture thickens and coats the back of a spoon (170–175°F or 77–80°C). Do not let it boil.

Step 3: Combine and Chill ; Remove the custard from heat and strain through a fine sieve into a clean bowl to remove any lumps. Stir in the cooled strawberry purée until well blended. Cover and refrigerate the mixture for at least 4 hours or overnight until fully chilled.

Step 4: Churn the Ice Cream : Pour the chilled mixture into an ice cream maker and churn according to manufacturer’s instructions (typically 20–25 minutes). During the last few minutes of churning, add diced fresh strawberries if desired. (If making without an ice cream maker, pour into a shallow dish and freeze, stirring every 30 minutes for about 3–4 hours until smooth and creamy.)

Step 5: Freeze Until Firm : Transfer the churned ice cream to an airtight container. Freeze for 2–3 hours or until scoopable.