Preparation

Cook the berries:

• Combine the berries with the 2-1/2 Tbs. sugar and 2 tsp. vinegar in a large nonreactive skillet. Put the skillet over medium heat and cook, stirring frequently, until the strawberries are soft and the liquid they release has reduced somewhat, 6 to 8 minutes.
• Let cool slightly, then transfer the berries and their juice to a blender or food processor. Purée until smooth and refrigerate until ready to use.

Make the base:

• 我n a medium heatproof bowl, whisk the yolks just to break them up, then whisk in half of sugar (1/4 cup). Set aside.
• 我n a heavy nonreactive saucepan, stir together the cream, milk, salt, and the remaining sugar (1/4 cup) and put the pan over medium-high heat. When the mixture approaches a bare simmer, reduce the heat to medium.
• Carefully scoop out about 1/2 cup of the hot cream mixture and, whisking the eggs constantly, add the cream to the bowl with the egg yolks. Repeat, adding another 1/2 cup of the hot cream to the bowl with the yolks. Using a heatproof rubber spatula, stir the cream in the saucepan as you slowly pour the egg-and-cream mixture from the bowl into the pan.
• Cook the mixture carefully over medium heat, stirring constantly, until it is thickened, coats the back of a spatula, and holds a clear path when you run your finger across the spatula, 1 to 2 minutes longer.
• Strain the base through a fine-mesh strainer into a clean container. Set the container into an ice-water bath, wash your spatula, and use it to stir the base occasionally until it is cool. Remove from the ice-water bath, cover with plastic wrap, and refrigerate the base for at least 2 hours or overnight.

Freeze the ice cream:

• Whisk the strawberry purée and the remaining 2 tsp. vinegar into the chilled base.
• Freeze in your ice cream machine according to the manufacturer’s instructions. While the ice cream is churning, put the container you’ll use to store the ice cream into the freezer. Enjoy right away or, for a firmer ice cream, transfer to the chilled container and freeze for at least 4 hours.