Fermentation is the oldest food technology on earth. It happens in our guts, in the soil, in every cup of coffee and most restaurants still throw the juiced lime away. At Baldío, Mexico City’s zero-waste restaurant, Chris Locke has built an entire philosophy around that lime: a Korean-style raw syrup, a lacto-fermented powder for seasoning, a tapache, and finally a koji-based shoyu. Four products, zero waste, from something already used.

In this conversation, recorded inside Baldío’s production warehouse in Mexico City, Chris unpacks the three real drivers of fermentation — flavour, health, and waste reduction — and why most kitchens only chase one. He explains why the menu at Baldío functions like an ecosystem, where removing one dish breaks six others, why consistency is the wrong obsession for any restaurant working with small regenerative farms, and how 200 litres of surplus corn vinegar a week is pushing the project toward a retail product line.

A UK chef who built his fermentation practice in Toronto and a circular innovation kitchen in Melbourne before arriving in Mexico City and waited four months for a job that didn’t yet exist, Chris brings a rare cross-cultural precision to a practice most people still associate only with natural wine. Fermentation as a tool for closing loops, building shelf-stable products, and making the economics of zero-waste food actually work.

HOW A ZERO-WASTE KITCHEN TURNS JUICED LIMES INTO CHUNG, TEPACHE, SHOYU, AND MARMALADE

Most restaurants juice a lime, use the juice, and discard the rest (typically 70 percent of the fruit by weight). At Baldío’s production kitchen in Mexico City, the discard is the beginning. The juiced peel and pulp becomes a chung, a raw fruit syrup, drawn from Korean preservation methods. The lacto-fermented pulp dries into a powder for tahin, a seasoning. From the same fermented base comes tepache, a traditional Mexican fermented drink. Finally, koji-fermented rice mold inoculates the remaining material into a shoyu, a soy-sauce-like condiment with preserved lime intensity. When the shoyu is strained, the solids become marmalade. One fruit stream, four distinct products, zero waste.

“It’s a really nice process where we take something that people would usually throw away or might throw away and turn it into three other products and finish with something that’s entirely consumable.” — Chris Locke

THE RESTAURANT INDUSTRY’S OBSESSION WITH IDENTICAL DISHES CONTRADICTS REGENERATIVE SOURCING

The restaurant industry has built itself on a contradiction: it preaches local and regenerative farming while demanding ingredients that look and taste identical week to week. Nature does not deliver uniformity. A lime from a small regenerative farm in one season differs from the next season’s harvest in size, flavor intensity, acidity, color. At Baldío, where the team sources directly from chinampa farmers, every delivery is variable. The response is not to reject the produce or standardize it into blandness. Instead, the restaurant guarantees consistency of experience, in a way that guests leave having eaten something delicious, beautiful, memorable, rather than consistency of recipe. This requires a different kind of skill from chefs: adaptation, creativity, and the humility to work with what the land actually produces.

“Nature is not consistent in what it produces, and there are huge amounts of variety and diversity, and that’s beautiful, and that’s why nature is beautiful.” — Chris Locke

ZERO-WASTE RESTAURANTS MUST TREAT THE MENU LIKE A LIVING SYSTEM, NOT A PRODUCT LIST

When Baldío moved toward zero waste, the menu stopped being a list of dishes and became an ecosystem. Every ingredient procured generates byproducts. Those byproducts must flow somewhere—fermented, dried, powdered, transformed—and reappear in another dish. Removing one dish from rotation cuts off the supply of a secondary ingredient, which then destabilizes five others. This creates operational complexity: if a corn-based dish underperforms in sales, corn byproducts (cobs, husks) drop, and the vinegar pipeline thins. The team must balance menu engineering with flexibility, sometimes swapping primary ingredients into gaps that secondary ingredients no longer fill. It mirrors the ecological logic Pablo Usobiaga described on the chinampas in the previous episode of this three part series : the system requires constant human attention.

“There’s a lot of it like any system needs to be maintained and it needs human interaction… we’re building something that is very similar to what nature represents as an ecosystem, and then we begin to close the loops on all of these things that would be loose ends.” — Chris Locke

KOEN AND CHRIS ALSO TALKED ABOUT

• How Chris’s fermentation gateway was lactoferments, just salt and vegetables, before his first batch of koji in 2018 started a chain reaction
• The natural wine world as an earlier adopter of spontaneous, indigenous-yeast fermentation than most restaurant kitchens
• Mexico’s own fermentation history: pulque, tepache, tejuino from Jalisco, and agave fermentation into mezcal and tequila
• Making miso from corn masa — koji from Japan, grown on Mexican rice, fermenting Mexico’s most iconic grain
• The meditative side of fermentation: the fermenter’s job is to curate conditions, then step back and observe
• What Chris still wants to ferment: ancestral dairy — cheese aged in sheep stomachs, Central Asian yogurt traditions
• The nerdy, welcoming WhatsApp groups where fermenters share across borders and cultures
• How the bar team at Baldío ferments its own alternatives to a standard spirits list, using only Mexican ingredients

RELATED INTERVIEWS:

• Pablo Usobiaga – Zero waste and sourcing from Chinampas and smallholder farmers, building nature’s favourite restaurant in a 20 million city
• Andres Jara – How a chef-butcher-farmer turned legumes into a scalable, clean-label food that rewards farmers
• Anthony Myint – Sourcing better isn’t going to change the food system, award-winning chef might have the silver bullet for system change
• Sam Kass – Get people access to carrots before talking about nutrient density, former Obama’s chef and nutrition advisor turned investor says
• Sherry Hess – Hijacked Flavour: reclaiming taste from the food industry
  

More about our guest:
Chris Locke is a British chef and fermentation specialist currently based in Mexico City, where he serves as Head of Fermentation & R&D at Baldío — Mexico’s first zero-waste restaurant, a collaboration between Arca Tierra and London’s Silo. He has built a career across the UK, Australia, Canada, and Central America around two fixed principles: locality and zero-waste cooking, with deep expertise in fermentation, preservation, and closed-loop food systems. At Baldío — which holds a Michelin Green Star — he works directly with Arca Tierra’s regenerative chinampa farms in Xochimilco, turning the supply chain relationship between kitchen and land into a live demonstration of what circular food systems can actually look like.

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