1. Set a clean bowl and a strainer close at hand.
2. Combine the cream, milk, sugar, and salt in a heavy-bottomed saucepan.
3. Turn the heat to medium and stir until the mixture is hot but not boiling.
4. Whisk the egg yolks in a spacious, heat-tolerant bowl. Temper the yolks by slowly adding one cup of the hot cream mixture while whisking vigorously.
5. Reduce the heat to medium-low and whisk the tempered yolks into the saucepan, creating custard. Cook, stirring constantly, until the custard thickens slightly and coats the back of a wooden spoon. Immediately strain it into a clean bowl.
6. Allow the custard to cool to room temperature (approximately one hour).
7. Add the passion fruit concentrate and mix well.
8. Refrigerate the mixture for 4–6 hours to ripen.
9. Place the cold custard in the canister of your ice cream maker and process according to the manufacturer’s instructions. The ice cream will be soft.
10. Transfer the ice cream to a container, cover, and freeze for at least 4–6 hours to firm up.
NOTE: For best flavor, always remove ice cream from the freezer 20 minutes before serving, or place it in the microwave for 20 seconds.