Tomato-Soy Barbecue Sauce

Virginia says of her barbecue sauce, “The older it is the better it gits. I does my sauce at least two days ahead and I likes the sweety-sour taste the sugar gives, but you can leave it out.” I don’t like the sweety-sour taste, so I do leave it out. To get a really nonsweet ketchup, I’ve started here with a version of Mary Randolph’s Tomato Soy from The Virginia Housewife (18