What do you do when a very large man, seemingly rendered speechless with drink, sits down at your restaurant table and starts to help himself from a bowl of potatoes wood-roasted with rosemary and garlic that you ordered as part of a spread of small dishes to start? At the newly opened Portobello you shrug, you go with the flow, you hope the waiters will move him on (they did) because here sharing is the ethos that burns as brightly as the fire in the pizza oven.

Started by Andrea Ippolito and Franco Ferro, two chaps from Sorrento who met while working in London, Portobello offers as one of the highlights Pizzametro — pizza by the metre — which they claim was created 40 years ago in Vico Equense, a small town on the Sorrento coast, as a means for a whole family to share a pizza. Since that time, they say, it has become a symbol of conviviality and a way of bringing people together.

The pizza, which can be ordered by the half or whole metre, is covered widthways in stripes of different ingredients so that members of a family — or a group of customers — can select their favourite bits. Wary of what I believe to be the lowering effect of melted cheese, I am not a great fan of pizza, but so crisp, thin, scorched and shardy, verging on volcanic was the base, so sweet and sunny the tomatoes used in the topping that I kept eating more of what, first time round, had been ordered as a kind of side dish. Apparently Franco Ferro, pizzaiolo, has in the past made a three-metre pizza for Jim Davidson. I dare say he would do the same for you and yours.

The restaurant occupies a site that was once the Greek/Cypriot restaurant Savvas but has been idle for the past few years. A deep courtyard is an asset — just about coming into its own as May sunshine drags its feet — and among the outdoor tables is a refrigerated boat displaying fresh fish. Although a cliché of Mediterranean seaside resorts, the toy boat and its contents, presumably sourced from Billingsgate or local suppliers, is more alluring than the catch from nets thrown into the Bay of Naples would be.

Inside, the wooden tables are designed for groups of friends sharing. This is not a Noah’s Ark where humans going in two-by-two are likely to get the best outcome. On both evenings we visited a noticeable, voluble proportion of the clientele was Italian. Knowledge of the language comes in handy when staff struggle with the scraps of paper that are the bookings system.

Antipasti and gli sfizietti (small dishes) provide scope for grazing. We liked the hot salt and peppery frittura of prawns and squid served with garlic mayonnaise and deep-fried mozzarella balls with spicy tomato sauce although one or two were not as molten inside as they could have been. The wood-roasted potatoes would have been improved by use of a waxier, more flavourful variety. We didn’t begrudge our new friend his share.

The section of pasta dishes is embellished by a list of specials. Sophia Loren has said about herself, “Everything you see I owe to pasta.” Linguine Sophia Loren featured sea bass as the main ingredient in the sauce, which I somehow feel might take Sophia by surprise, but the recipient thought it excellent. The plate was scraped clean.

From main courses cooked on the “charcoil [sic] grille”, tagliata (sliced grilled Scottish entrecote served with rocket and Parmesan shavings) and polletto al mattone (char-grilled baby chicken flattened under a brick) were good and agreeably unsurprising. More novel was Italian sausage made on the premises slit down its length and stuffed with smoked provola cheese. Well, I’ve made my feelings on melted cheese clear already. A sea bass brought in from the boat on the terrace and simply grilled was described as “just what was wanted”.

Cakes and patisserie are baked in the cooling wood-fired oven. Torta Limoncello and torta cioccolato were admirably restrained in sweetness, light and lyrical and on both evenings came as a gift. The staff at Portobello, particularly the owners and manager Massimo (short for Massimiliano he told us), seem truly to enjoy their work. Andrea and Franco are visibly thrilled to have, at last, a place of their own.

Glasses of Prosecco and shots of Limoncello are handed out to all and sundry. The result is a jolly restaurant. “It is so rare that restaurants are fun,” said one of my companions wistfully as she began making plans to bring groups of friends to this new source of satisfaction in Notting Hill. Our tablemate, the potato pincher, had wandered off into the night.