The walls of Betto e Mary are plastered with postcards, photos and Roman proverbs, but it’s the white sign at the back that caught my eye: a picture of a man wearing a tie with the caption “Io non posso entrare” (“I can’t enter”). Take another look at the walls and you’ll see the random selection of ties on display, apparently confiscated from diners who were unaware of the dress code.

When you come to Betto e Mary there’s no need to dress up. Just make sure you come with an appetite, and ideally carnivorous cravings. There’s no written menu. The waiter pulls up a chair at your table and recites the menu for the day, which usually ranges from classic Roman pasta dishes like carbonara and amatriciana to second courses that consist of most animals, and most parts of the animal. If you’ve ever wanted to try horse, this is your chance.

Officially, there are no vegetarian dishes on the menu apart from cacio e pepe, but if you ask nicely they’ll make you a vegetarian carbonara with courgette (after gently ridiculing you, of course).

Betto e Mary is cosy and chaotic, a Torpignattara institution that’s slowly being discovered by outsiders. Tipping is not expected at Roman restaurants, but it’s worth leaving a few extra euros just to hear the elderly Mary shout “Manciaaaaaaaa!” (“Tip!”)