Some of the tastiest and most tenacious regional variants hail from the South. Take the delicious pimento cheese burger, topped with that cherished Southern condiment pimento cheese: a piquant spread of cheddar (usually), pimentos, mayo, and spices. Dolloped atop a hot griddled patty, spicy pimento cheese melts and blends beautifully with charred beef. Versions appear throughout the Southern states, but Columbia, South Carolina, is the locus of the PC burger, as it's often called, according to the Southern food expert John T. Edge in his book Hamburgers & Fries (G. P. Putnam's Sons, 2005). "Every third joint serves one," he writes of Columbia and its environs, "and at least half of them are good."