Yuzu

A Japanese citrus with an aroma that reads somewhere between grapefruit, mandarin, and floral lemon — more complex than any of them alone. The fresh fruit is rare outside Japan; the bottled juice and yuzu kosho (a fermented chili-yuzu paste) are widely available and kitchen-practical.

In Japanese-Italian fusion it replaces lemon in most contexts: dress a crudo, finish a pasta sauce, brighten a vinaigrette. The flavor is more aromatic and less acidic than lemon, so it doesn't compete with delicate ingredients. Best substitute when unavailable: Meyer lemon.