Last year at the Torrance, California, robata bar Torihei, I came across a miraculous hot sauce called Yuzu-it, a briny spicy-sour condiment with subtle herbal notes that I found myself dousing on everything from chicken hearts to squid to grilled avocado. It’s made from green chiles, vinegar, sea salt, and most importantly, the juice of the Japanese citrus fruit yuzu, a knobby hybrid of the sour mandarin orange and the lemonlike Ichang papeda. This highly fragrant sour fruit, as you might have noticed, has been a trendy fine dining ingredient over the last decade or so. Yet rarely do you ever see it or its byproducts available in retail establishments.