Tlayudas [clae-yoo-das] are wonderfully messy open pizzas, sold at night on the streets of Oaxaca. Try them grilled, fried or baked in the oven.
Wash the spinach and shake dry. Heat a large pan, add the butter to it, then add the spinach and cook for a few minutes until the spinach has wilted down. Remove from the pan, squeeze dry and season with salt, pepper and a drizzle of olive oil.
Heat a large frying pan big enough to hold the flat breads or a flat griddle pan. Put one flat bread in the pan and sprinkle with a tiny bit of water to gently heat it.
Once slightly crisp, turn it over. Spread a layer of guacamole on first, followed by some grated mozzarella and a quarter of the rest of the ingredients. When the outer side of the bread is crisp and the mozzarella has begun to melt, fold the pizza over so it looks a little like an open calzone. Slide on to a plate and slice into pieces.
Serve the tlayuda with the habanaro salsa or a roast tomato sauce, with or without chipotles.