Swirlberry Ice Cream

Makes 1 quart

3/4 cup frozen strawberry, thawed and halved (about 3 ounces)
2/3 cup frozen raspberries, thawed (about 3 ounces)
1/2 cup sugar
salt
2 cups heavy cream
1 cup milk

In a small saucepan, combine the strawberries, raspberries, 1/4 cup sugar and a pinch of salt.
Bring to a simmer over medium heat, stirring, and cook until jamlike, about 10 minutes.
Let cool, cover and refrigerate until cold, about 1 hour.
In a medium bowl, whisk together the cream, milk, remaining 1/4 cup sugar and another pinch of salt until the sugar is dissolved; cover and refrigerate for 1 hour.
Using an ice cream machine, process the cream mixture according to the manufacturer's instructions.
Fold in the chilled berry mixture to make a swirl pattern and then transfer to an airtight container.
Freeze until firm, about 4 hours.