On a Monday morning last fall in in Cambridge, Massachusetts, a group of inquisitive visitors to Curio Spice Co. stood in a semi-circle and passed around small jars of spices. Many of the offerings were familiar to the group: they work together at Oleana, one of the country's foremost Middle Eastern restaurants, and they know their coriander from their cardamom. But then a new jar circulated and, one by one, like a string of old Christmas lights illuminating bulb-by-bulb, everyone's facial expression changed: eyebrows arched, eyes widened. This was something new. "It's like stars on my tongue!" someone exclaimed. "It's like Szechuan Froot Loops!" offered another. It was sansho pepper, the electrifying Japanese cousin of Szechuan pepper, which tingles taste buds with bright, citrusy heat. Most common in Japan as a counterpoint to sweet, fatty unagi, sansho is not well known in the U.S, at least for now.