The rind, or peel, of a lemon consists of two layers—the yellow zest (or the flavedo), and the white pith (albedo). The zest—where you’ll find all of the fruit’s aromatic oils—lends lemony fragrance to anything it graces, without the pucker.
Finding a suitable substitute for lemon zest in recipes can be tricky, but not impossible. Lemon oil, made from nothing but cold-pressed lemon rinds, is probably the most accurate substitute, taste-wise; but, if you’re unable to source a lemon, it’s probably also unlikely you have a stash of lemon oil. Here are some tips on how to utilize non-lemon lemon substitutes, to zesty effect.
Consider the task at hand.
To pick the most effective substitute, first think about what lemon zest was to bring to your recipe or dish at hand.
Is it Citrus scent you're after?
If you can’t get your hands on some lemons, instead sub in lime, orange, grapefruit, yuzu (!), pomelo (!!) zests instead. Overwhelmed by your now bountiful options? Consider the cultural context: Limes play well with Asian (fish sauce, ginger, turmeric) and Mexican ingredients (chiles, cilantro, tequila), while grapefruits and oranges complement Mediterranean ones (buttery olive oils, anchovies, fennel). Though none will replace lemon zest perfectly, each will add its unique flavor and perfume.
Or, General Freshness?
Sometimes lemon zest is added not for its specific flavor, but for its mere suggestion of freshness—like in a heavy ricotta filling for pasta, or a buttery shortbread. If this is also true of your recipe at hand, sub in finely chopped cooling herbs (especially lemony ones like sorrel, lemongrass, basil), a tiny splash of a young or fruit-based vinegar (aged wine vinegars can feel musty), or even a spirit or extract (I like Grand Marnier in oil-based cakes).
Consider how it’s to be incorporated.
The substitutes above are great for lemon zest’s usual state—finely grated (with a Microplane or box grater) and stirred in.
But, if you’re looking to infuse lemon flavor (like in pie fillings, spirits, vinegars) without having tiny, fresh things to chomp on—and again, don’t have any lemon oil on hand—try subbing in cracked coriander seeds, dried chamomile, lemon balm, or lemon verbena leaves. Once the flavor’s been imparted, strain them out.