In 2001, inspired by the multi-ethnic community of musicians in the multi-ethnic Roman quarter of Esquilino, pianist Mario Tronco decided to create an orchestra. His efforts to bring together musicians from Tunisia, India, Cuba, Hungary, Ecuador, Italy, the US, Argentina and Senegal is documented in Agostino Ferrante’s film L’Orchestra di Piazza Vittorio.

I’d been living in Rome just shy of a year when the film was released in 2006. It was shown at the Greenwich cinema here in Testaccio, a quarter that feels a world away from decadent Esquilino and the fringes of Termini train station, where I myself lived for two months when I first arrived in the city.

Early in the film there is a scene where a woman shouts, in hard Roman dialect, “immigrants out” – an an ongoing theme in the film, along with those of language, money, Italian bureaucracy and misunderstanding. But above the struggles, with Tronco’s infallible energy and compassion rises the impression that everything in Rome becomes, in some way, Roman. And under Tronco’s guidance, 10 musical traditions and languages are wrought together into compositions: Arabic disco meets Latin groove, Mozart meets Sahara blues and Sufi folk. It is joyful.

Like the orchestra born at this cultural crossroads, the Nuovo Mercato di Esquilino is a pulsing, multi-ethnic one: Egyptian butchers are butted up next to Hungarian ones, Bangladeshi fishmongers chant alongside Roman fruttivendolo, while young Ghanaians ferry vegetables on iron trolleys. Talk to anyone for more than a few minutes and it is clear there are struggles – you can feel them almost hanging in the air as they do in the film. Above them though, rises the music and life of a busy market, dozens of languages and customers converging into Italian, and just as many scents, all of them persistent and vital.

It is difficult to find coriander in Rome, but here the smell of it is omnipresent, along with cabbage leaves, spices and the cool scent of meat fat. Coriander is a flavour I used to find awkward: turns out I was the awkward one, and it is now one I crave – no other herb can quite hit that corner of my mouth. I buy it bunches with tufty roots from an Indian stall, and green chillies from the Ecuadorian couple. Back home, I pull Diana Kennedy’s The Art of Mexican Food from the shelf for the late Senorita Esperanza’s recipe for potato cakes, first made for me 15 years ago by a French friend living in Camden.

The cake are simple: 400g of boiled potatoes, crushed with your hands and mixed with 100g cheese – ideally queso anejo, but salted ricotta works, too – along with a whole egg and a handful of chopped parsley. You plop tablespoonfuls of the mixture into a frying pan with a finger of hot oil, press the top slightly and cook, flipping halfway, until both sides are golden.

There must be a table sauce with these cakes, according to Senorita Esperanza. The partners in the Mexican salsa are tomato, seeded chillies, onion and coriander,. Coriander wakes up in the presence of raw heat, becoming its true self; metallic and soapy flavours give way to something citrussy; sharp but soothing. Topped by a spoonful of salsa, the hot potato cakes are an absolute delight to eat.

And in the making, a Mexican recipe, taught by French women to English ones, then made in Rome with ingredients bought from an Bangladeshi and an Ecuadorian. If that isn’t the music of food, I don’t know what is.

Potato cakes with tomato, onion, chilli and herb salsa

Prep and macerate 40 min

Cook 40 min

Makes 12 small cakes

For the salsa

1 medium white or red onion, finely chopped

1 large, ripe tomato, finely chopped

1-3 moderately hot green chillies (traditionally serranos, but choose what is available), deseeded and finely chopped

1 small bunch coriander, roughly chopped

Salt

Photograph: Rachel Roddy/The Guardian

For the potato cakes

2 medium potatoes (approx 500g)

1 large egg, beaten

100g queso anejo, Romano cheese, salted ricotta or pecorino, grated

2 tbsp parsley, finely chopped

Salt and black pepper

Oil for frying

First make the salsa: Mix the chopped tomato, onion and chillies with the coriander leaves, adding salt to taste and moistening with a little water. Leave to sit for 30 minutes while you make the potato cakes.

Boil the potatoes in their skins until tender. Once cool enough, peel and then either crush the potatoes with your hands or a fork, or pass through a potato ricer. Add the egg, cheese and parsley to the potato, mix, then taste and season as required.

Pour enough oil to come 1.25cm up the sides of a heavy-based frying pan – the smaller the pan, the less oil you will need), and heat. When the oil is hot, add tablespoonfuls of the mixture to the pan, flattening each portion slightly with the back of a fork. Fry, turning from time to time, until the potato cakes are a deep golden colour on both sides.

Lift the cakes from the oil on to a plate lined with kitchen towel to blot, but then serve immediately with the salsa spooned on top.

You can make the cakes in advance: after blotting, lift on to a baking sheet lined with more paper towelling, and when you’re ready to eat, reheat them in an oven set to 180C/350F/gas 4.



