
Yuzu juice is the sour, aromatic juice of the East Asian citrus yuzu.
Lemon and lime with a little mandarin juice gets surprisingly close, and it is what most bars do. Either citrus alone covers the acidity and leaves the drink without the perfume that made the recipe name yuzu.
Salted yuzu juice
The common bottled form, preserved with salt and not interchangeable by volume with fresh in a delicate drink; in a savory one the salt is an asset.
Yuzu peel and zest
The prized part in Japan, and more aromatic than the juice with none of the acid; a recipe wanting yuzu aroma without sourness means this.
Fresh fruit is scarce outside East Asia, so the juice usually comes bottled and sometimes salted — which takes it a good way from freshly squeezed.
Fresh juice is used at once. Bottled yuzu is usually salted to keep it, so taste before you pour and count that salt as part of the drink.