Anytime husband John Pitts and I are 1) together and 2) close to Oxford, Miss. and 3) it’s anywhere close to eating time, we celebrate by heading to the downtown square for some of the best food in the state … or anywhere.  And the thing is, you can’t take a wrong step once you’re there. Oxford has an embarrassment of riches when it comes to places to eat. Take our newest favorite — Ajax Diner. This is real down-home cooking paired with a good beer selection, as if your Southern grandma cooked Sunday dinner at the local bar and invited the whole town. Best bets here are macaroni and cheese, sweet potato casserole and burgers. I decided to ignore the “List of Approved Foods for Patients with Malfunctioning Gall Bladders” my doctor gave me, and I went for the fried oyster salad (although in deference to The List, I didn’t eat all the cheese).  But a better list is “Things We’re Going To Try the Next Time We Go To Ajax:”  Black-bean chili with local ground beef, homemade pimiento cheese in a grilled quesadilla and the blackeyed-pea and catfish cakes. And maybe fellow Ajax fan Eli Manning will be there.