Just a few minutes after we left the car and started walking through some fields we’d found our first wild ingredient: hogseed. ‘The seeds are edible and they have quite an intense, citrusy flavour,’ says Imogen as she shakes a few of the seeds out of a dried up husk. ‘It’s similar to coriander so we use them to make a vadouvan (a sort of French spice mix) hogseed butter, which we cook carrots in before finishing them off on the barbecue.’ It’s pretty amazing – what looks like a dried up old weed actually contains tiny little bursts of flavour that taste like they come from somewhere much more exotic than an English park. ‘We’re slowly replacing our spice cupboard with foraged British ingredients,’ adds Ivan. ‘We use Alexander seeds instead of Sichuan peppercorns and hogseed instead of coriander – we’re hoping that eventually we’ll be able to replace the full range eventually.’

Our next discovery was more familiar – a patch of large sorrel leaves, full of tart sourness and bright citrus flavours. ‘The easiest way to identify common sorrel is that the leaves have two pointed tips at the base near the stem – if it’s rounded then it’s not sorrel,’ explains Ivan. ‘You pay a fortune for this so it’s always great to find it.’

A couple of metres away from our sorrel discovery was one of the most surprising things I tasted during the whole morning – a tiny patch of vetch. At first I couldn’t distinguish it from the grass, but on closer inspection they were there: tiny leaves with little curled tips. To me, it looked like any other small green plant, but Ivan and Imogen excitedly talked about how it has a flavour almost indistinguishable from fresh peas. I tasted a little sprig and they were right – it was exactly like a pea shoot, growing wild right there in amongst the damp grass below our feet. Apparently when it’s a little warmer they will produce beautiful little edible purple flowers, and even grow little pods to boot.

These three ingredients – hogseed, sorrel and vetch – were perfect examples of the range of flavours to be found in the British countryside. The fact that we found them all within an hour of walking through a bit of greenery in London suggests that there’s even more to be found outside the city, and if you know what you’re looking for a quick stroll can become very bountiful indeed. To demonstrate this, Ivan and Imogen laid out a picnic highlighting some of their favourite wild ingredients. There was a fougasse bread flavoured with charlock seeds (a sort of wild mustard) which we stuffed with foraged confit mushrooms with a little cured egg yolk on top. There was a damson syrup used like a cordial to flavour water. There were some incredible jelly-like wood ear mushrooms coated in dark chocolate which tasted an awful lot like Turkish delight. The highlight, however, had to be a gorse panna cotta – it had such a pronounced vanilla flavour, yet there wasn’t a trace of vanilla in them.

‘We’re not looking to make dishes that taste really strongly of certain ingredients – we’re looking to make dishes that taste really nice,’ says Imogen. ‘The gorse panna cotta tastes delicious, and the fact that it’s flavoured with gorse instead of vanilla or coconut is what makes it interesting. It’s the same with a lot of our dishes; they’re not in-your-face or overwhelming to the point of being unpleasant, we just want to show people that many of the ingredients we like from all over the world can be replaced with something growing right here in the UK.’

It’s this that makes Native such a success. Rather than putting foraged ingredients front and centre, they’re subtly added to dishes to season or highlight other flavours we know and love. Alexander seeds are used to add tang to a butterscotch sauce, for instance, while slightly bitter herbs are infused into stock syrups to be used in cocktails and other foraged plants are dehydrated, preserved or powdered to be used as a seasoning. After all, you could put all the weird and wonderful herbs in the world into a dish – but just because they’re edible doesn’t mean they always taste good in their natural state.

Of course, not everything on the menu at Native is foraged. When it comes to vegetables, meat and fish, Ivan and Imogen make sure the suppliers they work with are as sustainable as possible, favouring game in the colder months and rare breed meats throughout the year. The way they come up with the day’s menu is unique, too. ‘We always take the whole animal rather than asking for 100 sirloin steaks or something, because that might mean the rest of the meat is thrown away,’ says Ivan. ‘A deer has two fillet steaks on it, for example, so we can only create two dishes from them and when they’re gone they’re gone. It means we can’t always offer everyone who comes to us for dinner the exact same thing on a given night, but if the fillets have been sold there’s always another cut to replace it until the entire animal is used up. It also takes the stress off the food chain a bit and it makes us more creative in the kitchen.’

Sustainability is obviously important to Ivan and Imogen, as is their zero-waste approach to running Native. As well as getting in whole animals, using foraged ingredients to take the strain off the food chain and working with farmers and suppliers who follow the highest ethical standards, they ensure as little as possible goes in the bin. They’ve become well-known for their ‘Chefs Wasting Snacks’ – a trio of little bites that are made from the trimmings and peels generated from preparing other dishes on the menu. They hope one day to open a sister restaurant to Native in the countryside, acting as a sort of community hub and working farm, and are looking at setting up a vertical farm in London to create a new form of farm-to-table dining.

‘It’s hard to be a restaurant like ours in the centre of London,’ says Imogen. ‘In a dream scenario we’d be fully self-sustainable, but to get one of the cutting-edge bio-digesters we’d need to do that costs about £1 million. We do as much as we can – we don’t throw anything away in the kitchen, make sure the plates always come back clean and try and take the stress off the food chain as much as possible. There’s always something else you can do, but for now we’re doing our very best.’

As we make our way back into the greyer parts of central London, it was hard not to be inspired by Imogen and Ivan’s passion for all things sustainable and foraged. Running Native means they don’t get as many chances to go out and forage as they used to – instead, they work with as many full-time foragers as they can. But whenever they have the chance they’ll venture out into the countryside – usually Sussex or Northamptonshire – and spend an afternoon just seeing what they can find. Since our trip my usual brisk walks with the dog have turned into slow-paced treks with my eyes set firmly on the ground, hoping to spot a patch of vetch or an elusive sorrel leaf. And while all I usually see is grass and things I’m far too inexperienced to actually identify (let alone dare to taste), I’m hoping one day I’ll be able to bring something home and cook with it. For now, however, I’ll leave it to the team at Native – after all, they are well-versed in taking these fascinating ingredients and turning them into seriously tasty food.