"It's mad how passionate you get about it," says John Dorrian, the largest Shiitake mushroom grower in the UK.
Of all the vegetables, the story of radicchio is most like Beauty and the Beast: a transformation from a wizened mess to an exquisite and on-trend ingredient.
What is the future for micro herbs? A decade or so after they first hit the Market, this popular product is shaking off its image as merely a pretty garnish on the plate.
Here on the Market, the run-up to Christmas is always frenetic – a buzzing build-up of phone calls, orders and deliveries until the festive break.
"The phone is just non-stop," says Hamish Mellor, as he checks on early harvests of Fenland celery.
"I'm getting two lives in one," says grocer Steve Moore, describing his plans to move to Chile in 18 month's time after 40 years at the Market.
The entrance, just a short stroll from Clapham North tube station, barely merits a second glance.
"We're feeding about 5,000 people a week. About 3,000 canapés are going out today," explains Jeremy Redgewell from Eden Caterers, as he loads up their van.
In this health-conscious era, the nation's appetite for salad is insatiable.