In a metal bowl whisk together simple syrup and egg yolks, set the bowl over a pan of simmering water and whisk continuously until the mixture reaches the ribbon stage (thick, pale yellow and forms a ribbon when the whisk is lifted). Remove the bowl from the heat, transfer the yolk mixture to the bowl of an electric mixer and beat on low speed until cool. Whisk in the mascarpone, karo syrup, milk and lemon juice and strain mixture through a fine sieve. Chill thoroughly, at least 4 hours but preferably overnight, then process in an ice cream machine according to manufacturer's directions.
In a small, non-reactive bowl toss strawberries with balsamic vinegar and sugar and set aside to macerate for a few hours, up to overnight.
Serve with macerated strawberries.
Yield: about 1 quart
*Note: To make simple syrup, combine equal parts sugar and water, bring to a boil, then simmer and whisk until sugar is disolved. Remove from the heat and set aside until cool.