Times Insider explains who we are and what we do, and gives a behind-the-scenes look at how our journalism comes together.

It all started in January when Choire Sicha, then Styles editor for the New York Times, asked his team a question on an internal messaging platform that read something like this:

Who wants to buy a subway tuna sandwich and send it to a lab?

America’s largest sandwich chain had just been sued by two customers in Los Angeles who said the meat Subway advertised as tuna was in fact something very different. Julia Carmel, a nightlife news assistant who writes for the Styles section, volunteered to do some research. She sourced 60-inch tuna sandwiches from three locations in Los Angeles, froze the meat, and shipped it across the country to a commercial food testing lab that two months later couldn’t conclusively determine what type of tuna it was – or if it was one species of tuna traded tuna at all. She recently recorded the odyssey in a 2,500-word deep dive, The Big Tuna Sandwich Mystery.

In an interview, Ms. Carmel spoke about her reporting process and how a tricky idea turned into a broader view of America’s food supply.

Are you a tuna fan?

I’m not a big tuna can person. I’m definitely more of a sushi eater. But I ate a lot of fish while working on this article. My editors also sent me messages – “I can’t stop thinking about eating tuna now!”

From that first piece of news in January until it was published last week, you’ve spent six months in tuna land. Where did you start

My first step was to contact a couple of labs. I said, “Hey, I’m overwhelmed here, but if I want to get a sandwich tested to find the protein that’s on it, can you help me?” And then our Food and Drug Administration reporter, Sheila Kaplan, helped me determine which labs were accredited because I don’t normally do food or science reporting.

Why order tuna? Sandwiches? Why not just tuna salad?

It is an extraordinarily strange thing to ask for six scoops of tuna. It would have blown my incognito status!

You’ve sent your samples to food testing labs across the country – twice after the first ones got lost in transit. Did you ever find out what happened to them?

You made it there – someone signed for the package. But they couldn’t find it, and they never told me what happened. I suppose the ice cream was pretty much melted when it was over one day, so anyone who got or opened it was definitely not happy. I suppose they have a warm and smelly tuna.

When the lab results were inconclusive, did you consider trying again?

At that point, the story wasn’t even about the results. The bigger topic wasn’t “Is that real tuna?” but “What does it take to find out where your food is coming from and why is it so difficult?”

If it is not Real tuna, is Subway to blame?

Everyone I’ve spoken to said if it’s anyone’s fault, it’s not Subway. It’s really hard to follow the process of buying canned food. Of course, companies should be responsible for making sure you get what you order, but by and large you are asking them to get you the cheapest product in the fastest possible way, whenever you want it. Do I expect them to cut corners if I want a $ 6 sandwich with these special toppings at 3am? That’s asking a lot – and it shouldn’t necessarily be – but if you put it that way, we have such a convenience culture. We need to find more equitable and sustainable ways to get our food.

You have no scientific background. How did you go about reporting a technical story?

My two anchors were Caity Weaver’s glitter article and Jonah Bromwich’s story about whether hot dogs contain human meat. I was hoping to produce incredibly playful, informative coverage that took you through something you hadn’t thought of. A scientist would use a whole paragraph to explain a lot of this, so he had to figure out how to take a very complex thing and keep its integrity while making it understandable to the average reader. My first draft has to be 4000 words so thank goodness for the editors.

What was the most surprising thing you learned?

It’s overwhelming that there are 15 different types of fish that the FDA can call tuna

Million Dollar Question: Is It Tuna?

I think it is likely. I can’t imagine what motivation they would have for not doing this. That said, I’m not going to eat it anytime soon.