Preheat the oven to 325°F (163°C) and arrange ramekins in a deep baking dish.

Heat heavy cream in a saucepan over medium heat until steaming; remove from heat and stir in lemon zest. Let steep for 5 minutes.

In a bowl, whisk together egg yolks, granulated sugar, salt, vanilla extract, and lemon juice until pale and slightly thickened.

Slowly pour warm cream into egg mixture, whisking constantly to prevent curdling.

Strain custard through a fine-mesh sieve and evenly pour into ramekins.

Pour hot water into the baking dish to reach halfway up ramekins; bake for 30–35 minutes until custards are set but slightly trembling.

Let ramekins cool in water bath for 10 minutes, then refrigerate for at least 2 hours, preferably overnight.

Before serving, sprinkle granulated sugar evenly over custards and caramelize with a kitchen torch or broiler until golden brown.

Allow caramelized sugar to set for 1 minute. Optionally garnish with fresh berries or mint.