Sunny citrus fruits are in season during the winter months—just when we need them to cheer us up—so now is the perfect time to make the most of them. Consider the lemon. This humble kitchen powerhouse adds acidity and brightness to myriad dishes, from sweet to savory, often helping balance other flavors or providing some needed pizzaz. I always have a bowl of lemons on my kitchen counter. Lemon tea is the perfect drink for a mid-morning break, and just as ideal for a nightcap before bed. The freshly squeezed juice adds just the right amount of gentle acidity to salad dressings, an essential element of brightness to a classic roast chicken, and a refreshing finish to an otherwise heavy soup or stew. On the sweet side of the spectrum, lemon pound cake, made with olive oil and lemon zest, is one of my favorites—and only one of endless recipe …