The Secret Ingredient Your Rice Krispies Treats Are Missing

In the early 2000s, when Tomoko Yagi and her husband went to the movies in New York City, Ms. Yagi couldn’t find anywhere she could hang out afterward with a nice cup of tea and dessert. Back in her hometown in Japan, she could go to the ubiquitous wagashi (Japanese dessert) cafes that served not-too-sweet confections, such as the fresh fruit and jelly-based anmitsu or the shaved ice treat kakigōri, with a beautiful pot of green tea.

That’s why, in 2004, Ms. Yagi opened her Japanese teahouse, Cha-An, in the East Village. For the next couple of decades, the chill spot became a mecca for anyone who wanted to linger into the night, but not over a drink at a bar.

Recipe: Black Sesame Rice Krispies Treats

From the start, Ms. Yagi’s star menu item has been her black sesame crème brûlée. Deep, almost peanut buttery black sesame seeds underpin its nuanced layers: a dark custard base shielded under a thin, crackly sugar crust that shatters under the tap of a metal spoon, a sphere of black sesame ice cream sitting on top, a lacy cookie wheel wedged into it. All that complexity comes in a small but mighty package.

You don’t have to go to a Japanese teahouse in Manhattan to experience the wonders of black sesame, though it couldn’t hurt. Where white sesame tastes like nuts, rich with a single-noted mildness, “black sesame has a bitterness,” Ms. Yagi said through her interpreter. Sugar balances that intense, bittersweet bite, scaffolding flavors beyond just sweetness.