Although Del’s Charcoal Burgers is housed in an aging building, with blond bricks, a flat roof, and a Texas flag painted to look as if it were unfurling in the wind, it shows no signs of decay. A few things have changed in the surrounding neighborhood since it opened, in the Dallas suburb of Richardson, in 1957. A hookah shop and a halal eatery are now part of the retail mix, which also includes a barbershop and an accountant’s office. A block away, a DART Rail line juts out on an overhead track. Beyond that is the eight-lane roar of Central Expressway. In an ever-moving world, still points are needed, and Del’s is that kind of place.The first time I heard of Del’s was after…