Our world abounds with shells and leaves and peels and bones that demand faith from those who wish to treat them as edible. Citrus peels are different. We all, at least unconsciously, recognize that the peels of oranges and limes and lemons and grapefruits are key to the pleasure of eating citrus itself—at least as an olfactory herald, a creator of the anticipatory gust that wafts upward when you first dig a nail into a mandarin, or cut a lemon in half. We know that there’s something worth keeping in those petals of shiny yellow and green and orange, at least from watching bartenders twist them into cocktails to release their volatile oils. As hard as it can be to see the promise in a picked-clean chicken carcass or tough fennel tops, it’s easy enough to tell that citrus peels are good.
It’s another thing, though, to actually make use of them. One hurdle is technical: once you’ve got a fruit out of its peel, or the juice out of a fruit, the rind that remains behind is floppy and structureless. Have you tried to zest a squeezed lemon? Have you zested your knuckle instead? Have you registered that knuckle zest is less versatile than the lemon kind? Ideally, each of us would commit to removing the zest from our citrus before cutting it in half to juice, or peeling it to eat. Like a lot of people, however, I’m not ideal. I have a steady enough disposition to do the right thing about thirty per cent of the time. The rest of the time, when I need lime juice for guacamole, or lemon wedges for chicken cutlets, I fail to take the extra twenty seconds it would require to pull out a zester—a whole extra tool!—and execute the plan.
Here is how I compensate for this seemingly permanent flaw in my character: I go ahead and zest my lemons and limes and, hell, even oranges right when I bring them home, or a day later when I open the refrigerator and see the fruit and am reminded to do it. This decreases the citrus’s life span somewhat—the peel is what protects the fruit inside it. But I’m forgiving of slightly dried or sunken fruit; I figure it’s better to have two ingredients—zest and fruit—in passable shape than just one in superb shape. If you don’t have a zester, you can use a Microplane or a cheese grater, or you can take a sharp knife and carve the outermost, oily, brightly hued layer of skin off in strips, which can be chopped by hand into zest, or dropped whole into ice water, or seltzer, or the cavity of a roasting chicken, or, or, or.
Zest is a miracle ingredient, because it offers the flavor of the fruit it came from in ultra-distilled form. This means that a very little bit goes a very long way. I have tested how far by devising a recipe that I can only think to transcribe like this: Store leftover boiled potatoes in a recently emptied zest container until they become citrusy and delicious. There’s no lazier way to reheat rice, while also changing it enough to ward off boredom, than by putting it in a little pot and adding a drizzle of stock or water, some butter, and a hefty pinch of lemon zest. Sure, it’s just lemony rice. But lemony rice is great! Here’s a really weird one: take leftover boiled egg yolks, smash them up, add a little pounded-up garlic, a tiny smidge of Dijon mustard, lemon or orange zest, and olive oil. Stir the mixture like your life depended on it, then dollop it over asparagus, or toast, or newly boiled eggs. Or, if you have parsley, you can chop that up, mix it with any zest (including grapefruit, or clementine, or pomelo), garlic, and salt, and you have a version of gremolata, the perkiest sprinkle for anything from oatmeal to beef stew. Have you made citrus-zest vinaigrette? Why not?
Sometimes, the above advice notwithstanding, you will still find yourself looking regretfully at the pithy, juiceless half of a lime or lemon or orange that you recklessly squeezed without zesting first. There are good things to do with these peels, too, whether their pith is the very little bit you get from a mandarin or the insulation-level stuff on a navel orange. One strategy is to make citrus kosho, the Japanese fermented condiment. (I do this following the method of Jori Jayne Emde, a virtuosic fermenter: she grinds the peels in a spice grinder with chilies and salt, sprinkles the mixture with a little orange juice, then lets it cure.) A more straightforward strategy is to let the peels dry out. This can be accomplished by putting them on a baking sheet by the window, or outside on a fire escape, or in an oven turned on very low. The goal is for the peels to become dry enough that they can be ground into a powder using a spice grinder or a mortar and pestle.
Then mix the powder into sugar to make citrus sugar; it will taste surprising and fancy; sprinkle it on cookies or banana bread or yogurt. Or, instead, mix it with a combination of salt and dried chili flakes. Then wet the rim of a glass, roll it in the citrus-chili salt, and fill the glass with ice and mezcal. Or cut up fruit and dip it into the citrus-chili salt. Imagine that you’re milling around outside, surrounded without fear by other humans, and a vender has handed you the fruit in a plastic bag and asked you whether you want it doused in hot sauce.
Citrus sugar or citrus salt will store for a few years. What will life be like in a few years? Wherever you are and whatever is going on, your cooking will taste better owing to that odd period when you gathered your leftover shells and leaves and peels and bones, and resolved to let nothing go to waste.
