A cross between a mandarin and a papeda (a subgenus of Citrus) and with a flavor somewhere between a lemon and a grapefruit, this Japanese fruit is the basis of ponzu sauce. Yuzus are about the size of mandarins but with yellowish-green dimpled skin. The fruit is filled with large inedible seeds, so they’re generally only used for their juice and zest. The yuzu’s mild sourness adds a bright addition to a marinade or salad dressing.