Southerners have no monopoly on classic American potato salad enhanced with all sorts of other ingredients and dressed primarily with mayonnaise, but they do draw a strict line when it comes to the variety of potato. Round, red boiling potatoes are the cardinal rule in the South (russets and other baking potatoes are considered too mealy and starchy for potato salad), with the only other acceptable type being yellow-fleshed Yukon Golds. “Tater” salad is almost as popular as coleslaw with pork barbecue in the South, and rarely will you find fried chicken or any baked ham without this salad on the side. The only other cardinal rule is never to undercook or overcook the potatoes (they’re perfect when easily pierced with a small knife). Remember that they continue cooking when simply drained in a colander and do not need to be doused in cold water. All mayonnaise can be used in this recipe, but the sour cream does add a silky fluffiness to the dish.