Bean-Filled Masa Flatbreads with Seared Steak and Salsa Verde

Mix the masa dough. Tip the masa harina and salt into the bowl, pour in the boiling water and stir with a spatula until a soft dough comes together. Cover with the damp tea towel and leave to rest for 20 minutes so the corn flour fully hydrates and turns pliable rather than crumbly.

Check the texture. Flatten a small piece of dough between your palms; if the edges crack more than a few millimetres, it's still too dry. Knead in warm water, 2 tsp at a time, until it feels soft and just slightly tacky, which is what lets you shape the ovals without tearing.

Char the salsa vegetables. Heat the grill (broiler) to high and spread the tomatillos, jalapeño, onion and garlic on the lined tray. Grill for 8-10 minutes, turning once, until softened and blistered with dark spots, since that light charring brings a smoky depth raw tomatillos don't have.

Blend the salsa verde. Tip the charred vegetables into the blender with the coriander and salt, then blend until fairly smooth. Set aside to cool while you get on with the rest; the sharp acidity of the tomatillos mellows a little as it sits.

Cook the bean filling. Warm the oil in the frying pan over medium heat, then stir in the garlic and cumin for about 30 seconds until fragrant but not browned. Add the beans and water and mash with a potato masher, cooking for 4-5 minutes until you have a thick paste that holds its own shape, which dries the beans so they won't turn the dough soggy later.

Portion and rest. Spread the mashed beans on a plate to cool for 10 minutes, then divide into 4 equal portions. Wipe out the pan, and divide the dough into 4 pieces of about 170 g, keeping them covered so the surface doesn't dry and crack.

Fill and shape each oval. With damp hands, shape one piece of dough into an oval and press a deep groove along its length. Add a portion of beans, pinch the dough closed over the filling and roll into a log about 12 cm long, sealing well so no beans peek through.

Press into flatbreads. Heat the oven to 100°C (80°C fan) with the rack and tray inside to keep cooked flatbreads warm. Put each log inside the opened freezer bag and press with the flat-bottomed pan into an oval roughly 22 cm long and 6-8 mm thick, smoothing any cracks with a wet finger so they don't split during cooking.

Dry-cook then fry. Heat a dry frying pan over medium-high heat and cook one or two flatbreads at a time for 3 minutes per side, until the surface looks dry and speckled brown. Add 1 tbsp oil per flatbread and fry for 1-2 minutes per side until the edges crisp, then keep warm on the rack in the oven; the dry stage sets the crust before the oil adds the crunch.

Season and sear the steak. Pat the steak dry and season all over with the salt and pepper. Wipe out the pan, add the oil and heat over high heat until just smoking, then sear the steak for 3-4 minutes per side, cutting it in half first if needed to fit, until well browned and an instant-read thermometer reads 63°C in the thickest part.

Rest and slice. Move the steak to the board and let it rest for at least 3 minutes before slicing thinly against the grain. Resting lets the juices pulled to the surface during searing redistribute, so the meat stays moist instead of pooling on the board.

Assemble and serve. Mix the diced tomatoes and chopped onion with half the coriander for the topping. Spread each warm flatbread with salsa verde, pile on the sliced steak, the tomato mixture and crumbled queso fresco, scatter over the remaining coriander and serve at once with lime wedges.