"OK. So what the hell is Yuzu?
Short answer is it's a fancy Asian citrus fruit. An expensive, fancy Asian citrus fruit. Long answer is Yuzu (Citrus ichangensis × C. Reticulata) is a hybrid fruit of a Mandarin and some other, fancier citrus fruit called an Ichang papeda which I've never heard of before until looking at Wikipedia to answer the question of what the hell a Yuzu is. It's a knobby, ugly looking little guy and not really something you'd want to eat but its zest is super perfumed and intense. A gussied up mandarin or a tangerine. Most of the time people use its juice which is similarly pungent but has an amazingly intense, pleasant acidity. Similar to Truffle oil or Piri Piri peppers, Yuzu gained popularity a decade ago in the culinary world and for a hot minute you couldn't eat anything without it. Obnoxiously so. Fortunately, the over-hype has dissipated so we can go back to enjoying it. Like Radiohead."