Prepare an ice bath by filling a large stainless-steel mixing bowl with
halfway with ice and adding water. Place a clean, dry stainless steel bowl into
the bowl filled with ice. Set aside.
Combine sugar and cornstarch in a heavy-bottomed medium saucepan, stirring to
combine. Whisk in milk, then cream. Place saucepan over medium heat and whisk
continuously until the cream mixture bubbles and begins to thicken; about
5 to 8 minutes. Pour the gelato base into the bowl resting atop the ice bath;
stir the mixture occasionally so that it cools evenly.
Puree the strawberries in a blender or food processor. If desired, pour through
strainer into gelato base. (I do not strain.) Add lemon juice and stir to
combine. Add the vodka if using (helps prevent freezing).
Remove from water bath, dry bottom of bowl, cover and chill the base until
completely cold, about 3 hours.
When the base is thoroughly chilled, process in ice cream machine according to
manufacturer's directions. Transfer to a chilled container with a tightly
fitting lid. Freeze, covered, for at least 3 hours prior to serving. Let stand
at room temp for 10 minutes to soften slightly before scooping.
Makes about 1 quart.