We just had to pull over. On an overcast, sultry day the sun had yet to make an appearance, and the landscape around us, although verdant, felt a little dull.

But then – a patch of blue sky. Suddenly the light changed, throwing rays of warmth down through the soft grey clouds and hitting, perfectly, the spire of a distant church. The fields and vineyards around it no longer appeared a homogenous green. Instead, they sprang out emerald and olive, pea, sage and lime, each one seeming to occupy its own fold in the landscape.

We were spending the day driving around the Istrian interior, and there would be plenty more sudden stops like this one. Because at every turn, this corner of Croatia had another surprise up its sleeve.

In Grožnjan it was the café set up on the medieval honey-coloured battlements with views that stretched for miles. In Vižinada it was the crumbling Venetian square. And in Livade it was a giant truffle.

This was discovered in 1999 by Giancarlo Zigante and weighed a world record 1.31kg. When served up for dinner, it fed 120 guests and today a bronze replica of it can be seen in the entrance to the Zigante Tartufi store. Seeing this brings home the sheer size of this famed white truffle, but even more mouth-watering is the hunt for fresh treats in the Motovun forest that lies just outside the door.

Close to the river Mirna, we followed truffle hunter Ivica Kalcic and his dogs into the woods. Lolloping along in wellies, I tried to keep up with their fast noses as Kalcic explained that, while white truffles were not currently in season, black truffles would soon be forthcoming.

It seemed unlikely, but suddenly one of the dogs deviated from the path and began to claw at the dark earth. Kalcic swooped in with his trowel and within seconds I was holding several dozen euros’ worth of pungent, fresh black truffle.

Istria is serious about food and over the next few days we continued to tour its gastronomic highlights. We took a boat trip up the Limski Kanal, a deep ria that was the favourite haunt of local pirates, who used it as a base to attack the Venetians. Today it is used to cultivate shellfish, and we disembarked at Fjord restaurant, knocking back those oysters and devouring a mountain of mussels, all washed down with a delicious local malvazija wine.

Ruled from Venice (just a three-hour drive away) for centuries and later part of Italy, Istria exhibits plenty of Italian influence, from its road signs to its restaurant menus. And nowhere is this more striking than in the coastal resort of Rovinj, where the tower of the 18th-century St Euphemia’s Church dominates the town and looks for all the world like a miniature St Mark’s Campanile.

We strolled up here through the old town, weaving our way through cobbled streets, under baroque archways and past Venetian mansions, to reach the highest point in town and gaze out over the Adriatic. Croatia is said to have some of the cleanest seawater in Europe and the Adriatic certainly looks like it has nothing to hide.

We spent our days enjoying it, swimming at the Beach Club at our hotel, the Hotel Lone, located in the Golden Cape Forest Park a short seafront stroll around the bay from Rovinj’s centre. Here, the pebbly beach has undisturbed views of Lone Bay and, as well as the sea, there is an outdoor swimming complex, complete with whirlpools, waterfalls and water massagers.

By night we continued to gaze at the water, dining on the terrace of the Wine Vault restaurant in the Lone’s sister property the Monte Mulini or at Kantinon on Rovinj’s seafront boulevard. But it was not until our final night that we took the detour that made our holiday.

Wandering in the dark through Rovinj’s old town we spotted a couple disappearing down a flight of stone steps, seemingly straight into the sea. We followed and found ourselves in Valentino, a cocktail and champagne bar whose terrace is literally on the rocks.

We grabbed two cushions and sat right at the water’s edge, ordering Negroni cocktails and kicking off our shoes. The Adriatic lapped at our feet as we took in the view – nothing but water from here to Italy. For once I did not have my camera, and I was not sorry. This is one view that will be framed in my mind forever.