Cook the bacon, brown the meat. Set a very large (12-inch) skillet over medium-high heat. When hot, add the bacon and stir regularly until it has rendered its fat and pieces are crispy, 5 minutes. Use a slotted spoon to scoop the bacon onto paper towels, leaving as much fat as possible in the pan. Return the pan to the heat. Toss the meat with a good amount of salt and the pepper, then scoop it into the pan, spreading it into an uncrowded single layer and leave undisturbed for a couple of minutes. When the meat is richly browned underneath, give it a thorough stir, leave it for another minute or so, then sprinkle on the Worcestershire. Stir until all liquid has evaporated. Scoop the meat into a bowl, leaving behind as much fat as possible.
Finish the dish. If there is very little fat in the pan, add enough oil, lard or bacon drippings to coat it nicely. Return the pan to medium-high. When hot, add the onion and pepper slices, then cook, stirring regularly, until the onions have browned, but still have a little crunch, about 4 minutes. Stir in the meat. When it is warm, reduce the heat to medium-low and sprinkle on the cheese. Gently stir until melted, then sprinkle with the crunchy bacon and cilantro leaves. Serve right away (which I like to do directly from the skillet) with warm tortillas and salsa.