Sometimes when I'm asked what the secret is to a dish I've made, the answer is a specific little trick I've picked up from my mother or a cookbook. But more often than not, the big secret is not a secret at all. It's lemon.
Adding lemon juice or zest to a dish, sweet or savory, changes its whole flavor profile. Suddenly, a pretty good tomato sauce is brimming with complexity, a blackberry pie tastes like it's packed with a thousand perfect berries and all of summer, and braised broccolini isn't just a convenient side dish — it's the best part of the meal.
Actually a type of berry called hesperidium, the lemon was probably first used in food and drink more than 2,000 years ago in northwestern India. According to Lemons: Growing, Cooking, Crafting, the ancient Romans first introduced the fruit to Europe when they began trading with India around 100 A.D. However, Romans didn't take to the lemons' sour taste and used them as decoration rather than food. Lemons have since spread from India and Rome to the Middle East, Africa, China and the Americas, and the lemon remains one of the most widely used ingredients from continent to continent — and yet few people take full advantage of their seasoning potential.
Besides making your mouth water, the lemon's acidity cuts greasiness and heaviness and gives food a fresh, clean taste. Lemon juice can also change a food's texture to fit a variety of needs, as when macerating berries, tenderizing meat and "cooking" ceviche. Lemon juice contains citric acid, which helps break down fats, carbohydrates and protein.
But lemons aren't just useful for their juice — the zest contains lemon oil, which is where you'll find the most flavor-bang for your lemon-buck hiding. This is especially handy in instances where you want to add flavor, but not additional liquid, as with pie crusts. And, unlike unsubtle salt, too much of which will strangle the flavors in your food, lemon juice and zest play nicely with bitterness, sweetness, piquance and umami, helping them reach their full potential.
The lazy side of some of us is wondering: Why can't I just use vinegar to add acidity to my food? Vinegar does have the advantage of a much longer shelf life than lemons, though not an infinite one. But many vinegars also have their own flavors, whether rich and sweet or bold and fruity, which can be overbearing or clash with other flavors.
Lemons, by comparison, are inexpensive, easy to find, consistent in quality, and hard to use incorrectly.