This is a Chinese dish from the north-west that we don't see in America. It's very common around northern part of China as a brunch item.
The traditional selection of meat here is upper pork belly. By that I mean the part of pork belly right next to (or, on) the ribs, which contains more muscles than fat, so is leaner than the part used generally for bacon. The Chinese call it "5 layer meat", or 五花肉。however you can use beef as well, and I would pick the collagen-rich shanks and flank. This recipe is for stewed shank.
2lb of beef shank meat, bone-less, cut into small chunks
3tbsp of dark soy sauce
1/2 cup of your fav wine
1 onion diced
4 cloves of garlic crushed
1tbsp of chinese five-spice blend
1 small piece of ginger
2tsp of salt
Mix all ingredient together to marinade the meat, for about 20 minutes. Then brown the meat in either a pot or a wok. Add enough hot water just to cover the meat, cover and then simmer for 3 hours.
360 grams of AP flour (sorry, use your scale please!)
3/4 cup of warm water
1/2tbsp active dry yeast
Mix water, yeast and sugar together to proof the yeast for 10 minutes.
Measure 300 grams of flour, make a dough with the water/yeast mixture and the salt. This dough will be very wet, so you don't really need to knead it too much. Just make sure the dough is smooth outside. Let rise for 1 hour.
Add the rest of the flour (60 grams) to the dough, knead until smooth (this might sound odd, but it's important to make a "partially leavened" dough so that when cooked, it won't puff up like a pita.
Let the the dough rest for 20 minutes and divide into 8 equal portions.
Heat up your cast iron skillet on medium low.
Take a piece and roll out into a 1/4 inch thick tortilla. When skillet is hot enough (not too hot, because we don't want too much browning on this bun) place the tortilla in it without any greasing. Cover and cook for about 2 minutes and then flip, cover, and cook for another 2 minutes. Again, check the pic below - there's only minimal browning.
When done, let cook down a little bit and slice open, but leave the two pieces attached.
Take two chunks of meat and a tsp worth of juice, and chop it up! Mix in some chopped jalapeno, chopped cilantro and onion, and place it between the two sheets of bread. Still, leave the bread pieces attached.