Whisk together the egg yolks and half of the sugar. Set aside.
Combine the other half of the sugar, the milk, and the vanilla (if using paste) in a nonreactive pan. Bring to a boil, stirring the whole time.
Pour the hot milk mixture into the egg mixture very slowly, whisking the entire time. Whisk in the lemon juice, salt, and vanilla (if using extract).
Mix the ricotta in a separate bowl to break it up. Slowly pour the hot milk mixture into the ricotta in batches, whisking well after each addition to prevent lumps.
Place the bowl with the mixture in an ice water bath to chill. Churn in an ice cream machine according to the manufacturer’s directions. Store the ice cream in the freezer for 1 to 6 hours before serving.
To serve, trimmer recommends placing a few small scoops of ice cream in a bowl, scattering ripe strawberries on top, drizzling with a high-quality aged balsamic vinegar, and placing a shortbread cookie on the side.