Everything has to be fun at Mugaritz, even in the kitchen, where they play with potatoes by turning them into stone. The guests are served beautiful river stones that look like they’re plucked fresh from the stream that flows past the farmhouse. Then they’re challenged to eat them. This playful tradition has been going on since 2005.

In fact, it took a journey to a faraway land to make stones you can actually bite into. The Mugaritz team went to Peru in 2005, where they discovered the tunta, a pre-Hispanic technique used by the people of the Andes to conserve potatoes for times of need. The potatoes were submerged in flowing water for a day and left to dry in the sun for another. When food was scarce, they could be rehydrated and eaten.

So, the first culinary trompe l’oeil created at Mugaritz was inspired by a traditional Andean dish, providing endless moments of puzzlement and fun.

In order to make stones out of potatoes, we turned to kaolin and lactose, two ingredients that were unknown in gastronomy at the time and that we have been using ever since. We mixed kaolin – a white clay used in a number of industrial applications such as optic fibre, explosives, pharmaceuticals, and cosmetics – with lactose – a sugar substitute with a similar texture – to coat the potatoes. Grey colouring was used to complete the illusion.

Once the stones were ready, the guests arrived, expecting to sit down to a formal dinner, and were asked to eat with their fingers instead.

It was Mugaritz’s first dalliance with visual poetry, and the start of a lifelong romance. Some years later, in 2011, the International Journal of Gastronomy and Food Science published a scientific article written by Mugaritz about the stones.