In a large saucepan stir together sugar and flour. Gradually stir in 2 cups of the milk. Cook and stir over medium heat until thickened and bubbly. Cook 1 minute more. Stir about 1 cup of the hot mixture into beaten egg yolks; return to remaining hot mixture in saucepan. Cook and stir just until mixture returns to boiling. Remove from heat. Stir in vanilla, cardamom, lemon peel, and remaining milk. Cool slightly. Cover the surface with plastic wrap.
Refrigerate at least 2 hours or up to 24 hours. Stir in whipping cream. Freeze in a 4- or 5-quart ice cream freezer according to manufacturers directions. Makes about 2 quarts (16 servings).