Cleo the Friendship Bread sounds like a children's book. It could also be an offbeat coming-of-age movie. But it's neither of those things – instead, it was a simple initiative that would become the first step on the journey of a young, ecologically minded chef; one that would result in him winning gongs from the Sustainable Restaurant Association and the Soil Association, and see him become one of the best-known faces of London's sustainable food movement.

Tom Hunt is that chef. He's the founder of Poco, the self-described "seasonal British tapas" restaurant (the second of which is in Hackney's Broadway Market, the original in Bristol), as well as multiple sustainable food initiatives and food writing through his "umbrella brand" Tom's Feast.

"It was a take on the Herman the German cake," he says of the project that kicked off his fascination with sustainable food, "which is a friendship cake that you passed around. You feed it loads of sugar and yeast, and it grows.

"At that point I was going through my sourdough stage, so I created Cleo the Friendship Bread. It was a recipe for sourdough, where you receive a starter, feed it over a few days, and then it multiplies to the point where you can make a loaf of bread and then pass three more starters on to different friends, and then it goes on and on."

A nice social initiative, you might say, but here's the kicker: "That was really about the idea that if we're making our own food and taking it to that level, we're not going to waste a crumb."

In many ways, Hunt's first foray into something that involved more than just dishes on a menu could sum up his entire approach to cooking, and to food waste – the issue that's arguably at the very top of his agenda. He describes a kind of self-fulfilling prophecy: "The idea is 'How are we going to treat this ingredient with real respect?'

"When you value it to that degree, it really pushes you to think about the ethics of your produce. That's one of my key arguments for root-to-fruit eating: that by saving that percentage of the ingredient that's normally wasted – on average around 30% in the home or in a restaurant, or up to 50% of the food we produce globally – you're creating a budget for buying better-quality and higher-welfare produce, which you're then going to value more anyway, and eat in its entirety. It's a kind of cycle of improving your diet, nutrition and the planet – all through just really enjoying your food."

Hunt's argument seems blindingly obvious, but only now is it truly being rediscovered. In a time when convenience comes before all else, the damage being done to the global food system is just starting to be realised at scale. And a simple counter to it is, as Hunt says, to simply value your ingredients. From buying organic produce – proven by a recent independent study to be better for public health than those grown by extensive farming methods – to growing what you can yourself, and spending more money on better quality in smaller amounts.

After all, if you do that, you'll value those products more. It's easier, for example, to throw away half a pepper that's been grown in Peru and picked up from a local supermarket; it becomes harder to do so the more connected you are to its origin.

There's a reason Cleo the Friendship Bread was a catalyst for Hunt: "Bread is one of the most wasted food items there is," he says, "so root-to-fruit carried on from that idea about how we can really teach people to value food, and it took me into the idea of whole-food eating, but taking that quite literally – using whole grains, wholewheat flour, unrefined sugar – but also taking Fergus Henderson's philosophy for eating the whole animal a step further, and looking at how we can apply that philosophy to all of the food that we consume."

As Hunt says of his self-styled "root-to-fruit" philosophy: "It's really about re-learning to value our food, connecting with nature, and wasting nothing. It started from my ambition to reduce waste, but through ruminating over that, I came to the conclusion that it's as simple as the fact that we've lost touch with the value of our food, and that's why we're wasting it."

Hunt had a head start in that sense. His youth and adolescence was spent in the south-west of England, where he discovered a love not just of cooking, but of entertaining – "I really, really enjoyed food." he reminisces, "I enjoyed the thrill of cooking, and feeding large groups of people in celebratory situations, and making the party." He then worked with Hugh Fearnley-Whittingstall at River Cottage, rising to head chef under his tutelage and getting an education in what Hunt refers to as "strict, seasonal cooking, and standing by your morals."

I'm about strict, seasonal cooking, and standing by your morals

He went on to run a moveable café at various British music festivals, getting it to the point where "it was running itself, and I ended up enjoying the festivals a bit too much, letting the team get on with it, and partying. I realised it was time to get my head down and set up a restaurant space."

That space was Poco, originally in Bristol, and then in Hackney. Along with his Tom's Feast events, largely centred around traditionally wasted food, and his writing, he uses it as a mouthpiece for his philosophy – amplified by the industry awards he's picked up on the way. "We actually won a hat-trick of awards with the SRA – Best Independent, Best UK Restaurant and the overall Sustainable Restaurant of the Year award.

"It gives you credibility – you can talk the talk, but when it's backed up by awards that prove that you're walking the walk, it gives you a better platform to continue that work, which is really important to me. Having a voice to communicate ideas around animals, agricultural or agro-ecology, holistic cookery, and things like that is really special."

Now that Poco can be said to be, like the festival café that preceded it, "running itself", Hunt is doing what he's always done: making plans to push his philosophy further. He describes his move towards vegetable-forward cooking as a natural result of having learnt to cook seasonally: "I use more vegetables than most people in my cooking because I'm true to seasonality, and that means looking at which vegetables are in season.

"When I go to put a menu together, the first thing I do is look at what's in season and focus on those vegetables, and then work from there." It's hard to argue with – spring lamb and game are seasonal, of course, but meat doesn't tend to have the seasonal diversity that vegetables do.

Cooking seasonal veg with Tom Hunt:

But Hunt isn't satisfied simply by putting vegetables centre stage. Having recently turned vegetarian himself, he's overhauling his restaurants so they only serve meat and fish that's more than just environmentally neutral; it actually has a positive effect on the world around it.

"We're always trying to reduce our impact on the environment, on climate change, on reducing our carbon footprint," he says. I realised quite recently that we could have a positive effect. Instead of asking 'How can we do less damage?', we could ask 'How can we effect positive change?'."

Having decided his vegetarianism needed to have a tangible effect on the way he was cooking – not just the way he was eating – he stopped short of turning Poco into a vegetarian restaurant. "You can have a lot more power and emphasis when you're discussing how you can eat meat well, rather than just saying to people: 'Don't eat it.'"

So how does he intend to implement this on the menu? "It starts with the fish menu," he says, "from what I consider to be a sustainable menu of fish, serving things like coley and dab – but reducing that right down to oysters, because oysters are generally a really environmentally positive thing to farm: they clean the estuaries that they're grown in as they filter thousands of litres of water per day, and actually have a really positive effect on the ecosystem. It's about starting with those products and using them, and then educating people around why.

We've lost touch with the value of our food – and that's why we’re wasting it

"Meat's the same – we're going to have to really restrict ourselves to a few ingredients, and I'm going to start with pests: conservation bodies sometimes need to cull certain animals from the environment, like wood pigeon – which was one of my favourite games when I was eating meat – and beyond that, muntjac venison, and even squirrel, which is delicious. They would have been culled anyway, so they're essentially a living animal that would have been wasted. That leads on to other areas of meat that you can use in an environmentally positive way, such as ex-dairy cattle, billy goat – which would normally be culled as a part of the dairy industry – and also rose veal."

It's an ambitious move for Hunt. It's also one he didn't need to make, but one he wanted to. As the owner of two seasonal restaurants that presented vegetables as the stars of the show and were winning awards for their commitment to the environment, Poco was already leading by example. But Hunt recognises, as more and more chefs and diners are, that people like him can always go further; they can always do more to try to influence change outside of their dining rooms as well as just on their menus.

Cleo the Friendship Bread was the beginning of a story that's only just beginning: cooking can, in its own way, change the world. And Tom Hunt won't rest until he's done just that.

To read more about sustainability within the food and drink industry, take a look at our sustainability section.