America is in the midst of a hamburger arms race. Bacon, avocado, heirloom tomato, farmstead cheeses—hell, even chilies and wild mushrooms are positively so-mid-last-century. The new arsenal includes outré offerings like foie gras, duck egg, white truffles, boletes, kimchi and many other gourmet products never intended to be eaten within a bun, buttered or not. […]