Nick isn't a vegan, but he is trying to cut down on dairy.
So he has picked up a Fiery Tofu and Slaw sandwich from Tesco's brand new vegan range for his lunch today.
Tesco's vegan meals-to-go - launched this week - aren't flying off the shelf exactly, but there appears to be some interest in this central London branch, and not just from the ethically-minded.
"I like meat too much to give it up," confesses Joanna. But she likes the look of the Moroccan-inspired bowl of bulgur wheat, spiced beetroot and humus - she's also keen on vegetables. So she's taking one of those.
Tesco is betting that young professionals such as Nick and Joanna are the shape of things to come. And they could be right.
A third of the UK population claims to be "flexitarian" - that is, cutting back on animal products.
Moreover, veganism is currently flavour of the month, with backing from sports stars and celebrities from Arsenal midfielder Jack Wilshere to Jennifer Lopez.
This month, thousands have signed up to "Veganuary": a commitment to clean up your health and your conscience simultaneously, by shunning all animal products from bacon to butter for a month.
And retailers are banking on at least some of us sticking to this new dietary piety for the longer term too, though more often than not, they're sidestepping the word "vegan" in their branding.
Tesco has commissioned chef Derek Sarno, formerly senior chef at Whole Foods Market, to create ready-to-go meals that sound more appetising than virtuous.
There are crispy carrot "pastrami" and barbecued mushrooms, pumpkin falafel and sourdough pizza.
"For too long, vegans have been overlooked, with many offerings that are available seemingly created to appease rather than truly please," says Mr Sarno.
"Tesco has recognised the time is right to significantly expand its plant-based range and take it from a niche market right into the middle of the mainstream."
More than 3% of the UK population, identifies as vegan, a tripling in as many years, with signs that the numbers are continuing to grow, especially among "generation Z" consumers - the mini-millennials, still in their teens.
Vegan recipe books are on the shop shelves and veganism is a popular discussion topic online, as the internet makes it as easy to share links to films critical of animal farming, such as the popular "Cowspiracy", as it is to share an image of your multi-coloured, spiralised, plant-based lunch.
Other supermarkets, Sainsbury's, Waitrose and Marks and Spencer, also offer plenty of vegan food from soups to sauces, curries to canapes, substitute sausages and non-dairy cheeses.
"It's companies following the pound," says Simon Winch, chief executive of Veganuary, the charity trying to encourage consumers to sign up - and maybe stick with - the vegan lifestyle. "They see the demand is there."
Perhaps more surprisingly, budget supermarket Aldi also offers a long list of vegan-friendly products, from almond milk to potato waffles.
"Retailers have had a tough time and so they're seeking growth anywhere they can find it," says Molly Johnson-Jones, senior analyst at GlobalData Retail.
"You can charge more for premium and free-from products, so they're really trying to tap into this."
She says that if even the low-cost supermarkets, which stock a much smaller range of items than their bigger rivals, are choosing to give shelf space to vegan products, then it really is a sign its time has come.
"I don't think it's a fad," she says "I think it's a genuine shift."
Veganuary's Simon Winch thinks vegans are also shaking off an outmoded image of lentils and sackcloth.
"I think historically, people have looked at veganism as cranks in sandals, an uninspiring diet. But what we're seeing now is a fantastic range of delicious options and that's why supermarkets are now proud to put vegan word on it."
Although, in fact, most retailers tend not to, perhaps because of some lingering image problem, which might deter those just dabbling with the diet.
Cool and relevant
Data from market analysts Euromonitor suggests over the last couple of years, the value of products sold with a "vegan" label has actually fallen (once inflation is stripped out).
More often, products are labelled "free-from", healthy or plant-based.
So while Tesco's new range is entirely suitable for vegans, they're marketed somewhat counter-intuitively under the label "wicked".
"My aim from the start was to create recipes that were 80% healthy and 20% wicked," says chef Derek Sarno.
"Recipes that would delight vegans and give them the options they craved, whilst also attracting meat-eaters and encouraging them to try plant-based foods."
Mr Winch hopes that strategy will make veganism appear "sexy, cool, relevant". But on the whole, he'd rather see clearly identified products that would make life easier for vegans out shopping.