Bring cream, juice, and a pinch of salt to a simmer in a heavy medium saucepan over medium heat.
Whisk together yolks, sugar, and honey, then add half of cream mixture in a slow stream, whisking constantly.
Pour back into saucepan and cook over medium heat, stirring constantly with a wooden spoon, until custard thickens slightly and registers 170 to 175°F on an instant-read thermometer (do not let boil).
Strain through a fine-mesh sieve into a bowl and stir in zest. Chill custard, stirring occasionally, until cold, at least 6 hours.
Place a large sheet of foil (shiny side up) on a heatproof work surface.
Toast white and black sesame seeds in a large heavy skillet over medium heat, stirring until white seeds are golden, about 8 minutes, then transfer to a plate.
Heat sugar and honey with a pinch of salt in a 2 quart heavy sauce pan over medium heat, stirring often, until deep golden, about 5 minutes. Stir in sesame seeds and remove from heat.
Pour mixture onto foil, smoothing top and spreading into a 10-to 11-inch round with a metal offset spatula (mixture will be very hot), then cool to room temperature.
Invert brittle onto a cutting board and peel off foil.
Cut brittle into small pieces.
Transfer to airtight container.
Freeze custard in an ice cream maker in 2 separate batches. Fold 3/4 cup sesame brittle into each batch after freezing.
Transfer to an airtight container and put in freezer to firm up, about 4 hours.
Serve with remaining brittle if desired.
•Custard can be chilled up to 24 hours. •Ice cream keeps 1 week.•Sesame brittle keeps in an airtight container at room temperature 3 months.
