1. Beat eggs at medium speed with an electric mixer until frothy. Stir together sugar, flour, and salt until well blended. Gradually add sugar mixture to eggs, beating until thickened. Gradually add milk, beating until blended.
2. Cook egg mixture in a Dutch oven over medium-low heat, stirring constantly, 15 to 20 minutes or until a candy thermometer registers 170°. (Mixture should be thick enough to coat a spoon.)
3. Fill a large bowl or pan with ice; place Dutch oven in ice, and stir occasionally 10 to 15 minutes until custard is completely cool. Transfer mixture to an airtight container; cover and chill 8 hours. Stir in whipping cream, vanilla, and desired fruit blend.
4. Pour mixture into freezer container of a 1-gal. electric ice-cream maker, and freeze according to manufacturer's instructions. (Instructions and freezing times will vary.)