When life gives you lemons, make lemonade, the old adage says. That's good advice, but there's an assumption underlying it that ought to be challenged. What's wrong with lemons? A life without them -- from the culinary perspective -- would be sour indeed. I came to this deep, philosophical revelation while lounging at the backyard of some friends who live in California. Just a few feet from where I sat was their lemon tree, drooping with fist-sized fruit. It occurred to me that even those of us