Heat the oven to 180°C/Fan 160°C/Gas 4. Cut the wraps into triangles. Lay them in a single layer on 1 or 2 baking trays. Slide into the oven and cook for 5-8 mins till crisp and golden. Leave to cool. Turn the oven down to its lowest temperature.
Put the whole chipotle in a measuring jug. Pour over 100ml boiling water and leave to soften. Halve the tomatoes. Zest the lime and juice half. Set the zest aside. Put the lime juice in a bowl. Peel and finely slice the onion. Add to the lime juice with a pinch of salt. Scrunch together. Peel and coarsely grate the carrot. Add to the limey onion. Finely chop the coriander stalks and add to the carrot, then set aside to pickle.
Set the coriander leaves aside. Cut the lime half into wedges. Peel and grate the garlic into a medium bowl. Add 2 tsp cumin and ½ tbsp oil. Stir to make a paste. Add the beef to the bowl with some seasoning. Toss to thoroughly coat the beef.
Remove the chipotle from the water, squeezing it gently (keep the water). Cut a little bit of the chilli and taste it. It should be smoky rather than spicy. Finely chop the chilli and stir as much you like (or dare!) through the créme fraîche. Add a pinch of salt.
Heat a frying pan till smoking hot. Throw in the beef strips and cook for 2 mins, stirring till browned. Remove from the pan and cover with foil. Place in the oven to keep warm.
Place the pan back on the heat. Add in the halved tomatoes with a pinch of salt (no oil needed). Cook for 3-4 mins till slightly charred and deflated. Pour in the smoky water from the chipotle. Cook for a further 4 mins till the liquid has almost evaporated and you have a chunky tomatoey sauce.
Place the nachos onto a large platter. Spoon over the chipotle tomatoes. Scatter over the carrot and onion. Finish with the beef. Drizzle over the chipotle créme fraîche and sprinkle with coriander leaves and lime zest. Squeeze over wedges of lime to taste. Serve with a handful of salad leaves each.