A charming little pizza joint in south city, Mr. X turns out pizza that isn’t high-falutin’ or trendy — just delicious. The basic hand-tossed crust is chewy and tasty, the sauce is a little sweet and a little spicy, and the cheese is beautifully blistered in the oven. The basic toppings are available (pepperoni and sausage are always good bets), but for a change of pace try the “Mr. X,” with chicken, green peppers and mushrooms, as well as salami and the Bosnian dried beef known as suho meso.