It’s early. The sun’s rays are just beginning to trickle down the streets of Valencia’s old town, but the stalls of the city’s Mercado Central are already doing a thriving business. There’s a queue at the deli, and the man behind the counter is cutting thin strips of Serrano ham in double time. He spins from one customer to another, dodging between stocky ham legs that hang from the front of his stall like fat wind chimes. As for seafood, tuna, sea bream, anchovies and huge pink langoustines sparkle in the ice. A stand here specializes in snails; another only sells saffron.

Among them all, in the spotlight in the heart of the Mercado Central, fruits and vegetables – plump, richly colored and all grown in La Huerta (L’Horta in Valencian), a patchwork of neat market gardens that unfold for 28 km² around from the city. Encarna Folgado, owner of Frutas y Verduras Folgado, has run a stand here for over 45 years, buying seasonal vegetables directly from farmers who work the fields of La Huerta. If you need to buy the beans used in a traditional Valencian paella, you come to Folgado.

“The ferraura should have a bright green color, but not too intense,” she tells me, referring to the horseshoe-shaped beans that almost spill out of their cases. ratchet, a red and green bean, “should be a few centimeters wider and thicker, but only a little”. And as for the butter beans, which I see bulging through their crates, “the best (the ones) to eat are when they start to turn from yellow to green.”

Next to the beans are spongy heads of broccoli, waxy red peppers, fatty bulbs of garlic, and spring onions the size of batons. They are all part of an incredible abundance of produce grown every year in La Huerta, despite the fact that its fields surround Spain’s third-largest city. The secret is an ingenious maze of canals, ditches, weirs and sluices invented by the area’s Moorish rulers 1,200 years ago.