How to Make It
Set a fine-mesh sieve over a bowl and set the bowl in an ice-water bath. In a medium bowl, whisk the egg yolks with 1/4 cup of the sugar. In a large saucepan, combine the milk, cream and the remaining 1/2 cup of sugar and bring to a simmer, stirring to dissolve the sugar. Gradually whisk the warm liquid into the egg mixture, then return it all to the saucepan. Cook over moderate heat, stirring constantly, until the custard is thickened slightly, about 4 minutes. Strain the custard into the bowl and stir in the sesame oil, vanilla and salt. Let cool.
Pour the custard into an ice cream maker and freeze according to the manufacturer's instructions. Transfer the ice cream to an airtight container and freeze until firm, at least 2 hours.
In a small saucepan, cook the sugar over moderate heat, swirling the pan until melted. Continue to cook, undisturbed, until a deep-amber caramel forms, about 2 minutes. Remove the saucepan from the heat and carefully add 1/2 cup of water. When the bubbling subsides, return the caramel to moderate heat and cook, whisking constantly, until any hardened caramel is dissolved and the sauce is slightly thickened, about 3 minutes. Transfer the caramel sauce to a small pitcher and rinse out the saucepan.
Add the heavy cream and honey to the saucepan and bring to a boil over moderately high heat. Remove from the heat and whisk in the tahini. Transfer the tahini cream to a small pitcher.
Scoop the ice cream into bowls and drizzle with the caramel and tahini cream. Top the sundaes with the crumbled halvah and crushed sesame candies and serve.
Halvah is a Middle Eastern confection made primarily from ground sesame seeds and honey. Look for it at candy stores and at specialty shops.