Place the sesame seeds in a dry, wide skillet. Shaking the pan frequently, toast the seeds over a medium flame until the seeds start to crackle. This can take anywhere from 2 to 5 minutes, depending on the thickness of your pan. It's a bit hard to tell when they're toasted, since they're black and won't change color, and they don't give off much fragrance, but crackling is a good sign. Let the seeds cool, then whizz them in a food processor until they turn into a paste, scraping down the sides of the bowl occasionally, 2 or 3 minutes.
Make the ice cream base:
Scrape out the black sesame paste into a medium saucepan, and add the milk, vanilla seeds and pod, sugar, and salt. Warm over a medium flame, stirring occasionally, until hot and steamy. Cover the pot and let the mixture steep at least 10 minutes or longer.
Meanwhile, place the egg yolks in a medium bowl. Place the heavy cream in a different medium bowl, or in a large mason jar and set aside. Rewarm the milk if necessary. Very slowly, dribble the hot milk mixture into the egg yolks, whisking constantly, until you've added half the milk. Scrape the yolk mixture back into the pan and return to a medium-low flame. Cook the mixture, stirring constantly with a heatproof silicone spatula, until it thickens just slightly and/or registers 170ºF on an instant-read thermometer. Immediately pour the custard into the cold cream to stop the cooking.
Chill the ice cream base until very cold, at least 4 hours, preferably overnight, or up to 3 days.
Spin and chocolate-ify the ice cream:
Place the ice cream base in the freezer for 30 minutes to get it really cold, giving it a stir once halfway through. Place a loaf pan in the freezer as well.
Meanwhile, melt the chocolate by placing it in a dry, metal bowl set over a saucepan filled with hot water that is barely steaming (not simmering or boiling, or you will scorch the chocolate). Stir the chocolate until it is melted, and let it cool slightly. When the ice cream is churned, the chocolate should be fluid enough to drizzle, but not so hot that it melts the ice cream.
Churn the ice cream in an ice cream maker until it is the consistency of soft-serve. Spread 1/4 of the ice cream in the bottom of the frozen loaf pan, then drizzle 1/4 of the melted chocolate over the ice cream. Repeat until you've used up all the chocolate and ice cream. Freeze the ice cream until firm, at least 2 hours. Once firm, scoop the ice cream into storage containers. It will keep frozen for up to a few months (though good luck making it last that long).
I love love love my Kitchen Aid ice cream maker attachment, pictured above. It goes in the freezer for 24 hours, then the bowl and dasher (which "stirs" the ice cream) go right onto the stand mixer. Turn it on low, and it churns the ice cream in about 10-20 minutes.I found black sesame seeds in the bulk aisle of my co-op. The 10 tablespoons called for here yields about 6 tablespoons of toasted black sesame paste. If you can't find the whole seeds, you can probably substitute an equal amount of Japanese black sesame paste, though you may want to decrease the sugar in the recipe if the paste is sweetened.I like this ice cream best made with dark milk chocolate that has a 35-40% cacao mass. This has less sugar and dairy than regular milk chocolate, which only needs to have 10% cacao mass to be labeled as such. I'm partial to the dark milk bar from Recchiuti, but Tcho and Scharffen Berger make excellent dark milk chocolates, also. I found bittersweet chocolate a bit too assertive, though still quite tasty, so feel free to use it if you prefer. This recipe can also be made using 2 cups half and half and 1 cup heavy cream in place of the milk and cream.All ounce measurements are by weight.Nutritional values are based on one of eight servings.