In medium saucepan over low heat, stir together sugar, milk and eggs. Cook, stirring continuously, until mixture thickens enough to coat the back of a metal spoon, 10 to 20 minutes.
Remove from heat and let cool.
In a medium bowl, whip cream with electric mixer until soft peaks form. Beat in vanilla and lemon juice, and whip until medium-stiff peaks form. Fold whipped cream into cooled custard. Chill in refrigerator 8 hours or overnight.
Stir chilled mixture to recombine, and freeze in ice cream maker according to manufacturer's instructions.
