2 pounds small red-skinned potatoes, quartered1 pound bacon, chopped2 large eggs2 tablespoons red wine vinegar3/4 cup mayonnaise3 tablespoons whole-grain mustard6 scallions, finely chopped1 medium red onion, diced1 tablespoon sugarKosher salt and freshly ground pepper Put the potatoes in a medium saucepan and cover with cold water. Bring to a boil, then reduce the heat to…