Combine the cream, milk, sugar, salt, and lemon zest in a medium saucepan over medium-low heat. Stir frequently until sugar is dissolved and small bubbles start to form around the edges of the pan.

Whisk egg yolks in a medium bowl until light. Gradually pour 1 cup of the hot liquid into the egg yolks while whisking to temper the eggs.

Pour the tempered egg yolks back into the pan with the hot milk liquid and continue to cook, stirring frequently, until the mixture reaches 170-175 degrees F or is thick enough to coat the back of a spoon. Remove from heat and chill. This can be done overnight in the fridge or by transferring the mixture to a heavy duty zip tight bag and submerging in an ice water bath to speed up the process.

Just before churning, add the lemon juice to the chilled ice cream base. Pour into an ice cream maker and churn until it is the consistency of soft-serve ice cream. If desired, add mix-ins during the last minute of mixing.

Transfer to a freezer-safe container (I always use clean bread pans) and freeze for at least 4 hours to "cure" and harden.