I'm treading on thin ice. I'm in danger of becoming the obnoxious friend who always starts a story with tales of their travels, and this recipe is no different:
When I lived in Japan, I fell in love with black sesame-flavored everything, but my favorite of all was black sesame seed ice cream. We lived a few subway stops over from the city's zoo and botanical gardens, which I visited frequently (thanks to a very reasonably priced annual pass). On nice days I'd often treat myself to a black sesame ice cream cone, but even ordering in Japanese I wasn't always convincing enough. Sometimes the worker would come out of the stand, around to me, and physically point to the picture to make sure I really knew what I was getting myself into. Yes, yes I did. One black sesame ice cream cone, onegaishimasu.
My version is based on a lightly adapted version of Jeni's Ice Cream Base, with a little less sugar, a little more salt, and the addition of black sesame seeds (of course) and vanilla bean seeds. Yes, I'm sure you could substitute a small amount of vanilla extract for the vanilla bean seeds. But it makes my soul sing a little bit to know that some of the flecks are vanilla bean seeds mixing in with the sesame seeds—delight in the little things and all that. —Lindsay-Jean Hard
In a medium-large bowl, whisk the cream cheese and salt together until blended and smooth.
Fill a large bowl with ice.
Toast the black sesame seeds in a skillet over medium heat, shaking the pan occasionally. They are done when they start to smell nutty, about 3 to 5 minutes. As soon as they are done, remove the pan from the heat and dump the black sesame seeds into a small food processor.
Process the sesame seeds until they are finely ground and start to release their oil, getting past the point where you are just looking at ground sesame seeds—to the point where they stick to the sides of the food processor bowl. This will take more than 1 minute.
In a small bowl, whisk together about 2 tablespoons of the milk with the cornstarch to make a smooth slurry.
In a large (4+ quart) saucepan, combine the remaining milk, the cream, sugar, corn syrup, processed black sesame seeds, and the scraped vanilla seeds. Whisk the mixture together, bring to a rolling boil over medium-high heat, and boil for 4 minutes.
You might be tempted to throw in the split vanilla bean pod pieces too, but know that they will be surprisingly difficult to find and fish out later, so unless you like to make life difficult for yourself, this is not recommended.
Remove the mixture from the heat and gradually whisk in the cornstarch slurry. Then return the saucepan to the heat, bring it back to a boil over medium-high heat, and cook about 1 minute, stirring until the mixture is slightly thickened. Remove from the heat.
Gradually whisk the hot milk mixture into the cream cheese until smooth. Pour the mixture into a 1-gallon freezer zip-top bag.
If you blatantly ignored my advice and threw in the vanilla bean pod pieces, now is the time to try and remove them. Look for them as you are pouring the mixture into the freezer bag and try to avoid cursing my name. If you are unsuccessful, turn it into a game for your guests, like finding the plastic baby in a King Cake.
Submerge the sealed bag in the bowl of ice and let it stay there until cold, adding more ice as necessary, for about 30 minutes.
Pour the cold ice cream mixture into the ice cream maker and spin until thick and creamy.
Pack the ice cream into a storage container and freeze in the coldest part of your freezer until firm, at least 4 hours.