Tolosa market, San Sebastian, Spain: Centuries-old Basque Country farmers' market keeps tradition alive

For almost 800 years the farmers of Tolosa have spent their Saturdays doing exactly as they do today: rising early, while it's still cold and dark outside and loading their trucks – once their horses and carts – in the growing dawn light. They then journey into town past old farmhouses still quiet, tendrils of smoke drifting from stone chimneys, livestock beginning to stir.

It's market day. The farmers trundle in from the Basque countryside, from the beautiful hills that hold the key to the rich produce they have to sell, to the fruits and vegetables, to the meat, to the eggs, to the cheese. They've made their way to the same spot, to the place by the river that is now called Tinglado, a covered marketplace surrounded by white archways, where produce is spread across tables, and where the crowds will eventually descend.

This is one of Spain's oldest farmers markets. It predates the current Antipodean fascination with the concept by about, well, 800 years. As soon as the town of Tolosa was founded in 1256, when it was just a rough collection of farmhouses in a spectacular valley surrounded by steep, green hills, farmers began gathering on Saturday mornings to sell their wares.

The sun is shining the day I arrive in Tolosa, having made the much easier (and later) half-hour drive from San Sebastian, the popular Basque coastal enclave. They say you should never go shopping when you're hungry, so I've called past a local bar on my way to the market to grab a slice of tortilla and a coffee, passing over a few coins for the privilege, before making my way through Tolosa's ancient streets, along its narrow, cobbled walkways shaded by hanging laundry and Basque flags on the path towards Tinglado.

So much of what makes the Basque Country unique, and so amazing, is on sale here today by the river in Tolosa. The first thing I spot is cheese, most locally produced using milk from the sheep whose woolly forms dot the surrounding hills, sold in blocks or wheels. You see labels for Idiazabal, Larraitz etxegarai, bleu des Basques. If you show interest in the cheese, someone will scrape some off for you to taste, to help you decide what's good, and what's better.

It's busy in Tinglado today, the covered space reverberating with the sound of Euskera, the Basque language, with "kaixo" and "eskerrik asko" instead of hello and thanks. This is Basque heartland, the farmers dressed in flannel, the shoppers' heads topped with berets.

I eventually move past the cheese to see what else is being sold. There are tables filled with pork products, with cured bellies and local bacon, with chorizo and with local sausages txistorra, with cheeks, with legs. There's bread, too – mountains of it baked today and meant to be consumed within hours. There are fresh vegetables, of course: root vegetables – because it's winter – all the potatoes and leeks and onions you've ever seen. There are farm-fresh eggs displayed in big baskets from which shoppers can select. There's local honey. There are packets of dried beans including the famous alubias de Tolosa, black beans used to make hearty pork stews.