I am a compulsive purchaser of lemons. It's not rational. It isn't like the corner of Brooklyn I live in is an inexplicable lemon wasteland, or that there's any world shortage of those zingy citrus fruits. Nonetheless: Every time I return from the grocery store with a fresh bag of lemons, I usually find another three or four beauties already rolling around in the fridge. It's a sad thing to watch those bright, sunny orbs wither into uselessness, and there's only so much lemonade a lady can drink. So when my lemon count has reached an untenable level, I know just what to do: make fruit curd.Fruit curdis not a sexy sounding substance. Probably you've most often heard of the cheese variety, or of curds in the context of Little Miss Muffet's dietary habits. But don't be deceived: fruit curd is jam's more indulgent cousin. It's a luscious, tart spread that can be used on scones or dolloped in yogurt or baked into a crazy-good pie. In fact, pie was the first context I encountered curd, thanks to a pastry connoisseur friend of mine who lives in Southern California (her lemon excesses have more to do with lemon trees in the yard than weird grocery fixations). The last time I visited, weary from a long road trip, she presented her guests with a sort of inside-out lemon meringue pie: an airy, crisp meringue crust filled with just-sour-enough lemon curd. Sold. Lemon is the primary flavor for my curd, but you could easily use grapefruit, orange, or lime too. I've heard passion fruit, mango, rhubarb, raspberry, and blueberry is also great. All you really need is fruit juice. Fresh is best, but in a pinch, whatever you've got. (If grapefruit is your citrus of choice, reduce the juice first to give it a tangier bite, or leave it as is for something sweeter and milder.) The real trick about curd is that you need to watch it as it congeals at a low temperature on the stove. Do not multitask (as I alas, once learned firsthand) or you will end up with lemon-sugar scrambled eggs. Many curd recipes call for the butter to be added slowly to the pot and then the whole curd strained through a sieve at the end of the process in order to catch the not-so-delicious-flecks of egg white that tend to form. I've found that if you cream all the ingredients together before you put it in the pot, you can skip the sieving process entirely. My recipe is adapted from David Lebovitz' Meyer Lemon Curd and Lemon Tart, though I've learned to adapt the sugar levels to the sweetness of the juice and the tartness preference of whoever you're serving the curd to. Fruit Curd, Y'heard?