Combine the heavy cream, sugar, and kaffir lime leaves in a medium saucepan.

Bring the mixture to a simmer over medium heat.

Cook over moderately low heat, stirring occasionally, until the cream is slightly reduced (about 15 minutes).

Whisk the lime juice into the hot cream.

Strain the cream through a fine sieve set over a measuring cup.

Stir in the lime zest and salt.

Pour the cream into eight 6-ounce glasses.

Refrigerate for at least 2 hours, or until chilled and set.

Top the custards with sweetened whipped cream.

Garnish with quartered lychees, chopped mint, and a sprinkle of sea salt.

Serve immediately.