I saw this on the C5 TV series Mexican Food Made Simple with Thomasina Miers. I expect that the recipe is in her book of the same name, but I don’t own it (yet!).
From the TV show, the tacos are made with corn tortillas filled with poached chicken and tightly rolled, secured with cocktail sticks and then deep-fried until thick.
So, I poached a couple of chicken breasts in water, with a carrot, half an onion, a couple of bay leaves, some parsley stalks and a dried chipotle chilli. When the chicken was cooked, I let it cool and then shredded it before rolling it up in the tortillas.
Once fried, I served them with sour cream, guacamole, pickled jalapeños, grated cheese and a salad of lettuce and diced tomato.