The former Suits actor, who reportedly refuses to wear animal fur, guest-edited the September issue of Vogue.
"So over a casual lunch of chicken tacos and my ever-burgeoning bump, I asked Michelle if she would help me with this secret project," Markle said.
Back in 2016, the Duchess spoke about her 'part-time plant-based diet' to Hello Magazine, revealing: "I just try to avoid the things that I know are going to make me feel lethargic or sluggish. I eat mostly just fish and veggies – but I am also a foodie.
When I'm filming, I'm conscious of what I eat. I try to eat vegan during the week and then have a little bit more flexibility with what I dig into on the weekends. But at the same time, it's all about balance."
Markle has also spoken publicly about cruelty-free fashion, telling Good Housekeeping Magazine she loves 'cropped pants in vegan leather' - which reportedly caused a 67 percent increase in internet searches for 'vegan leather trousers'.
She has also been photographed wearing a pair of vegan Stan Smith shoes made by designer Stella McCartney - during her 16-day Royal Tour of Australia, Fiji, Tonga, and New Zealand with husband Prince Harry.