If your shoulder has a fat cap remove it with a knife. Rub the meat all over with kosher or sea salt and black pepper. Fat cap side up lattice the top and sides with bacon. With cooking string tie a few trusses around the meat to hold down the bacon. It will want to pull off as it renders.
Set up a charcoal grill in the indirect method and place a disposable pie tin on the lower grate next to the coals. The shoulder will render quite a bit of fat. You may want to add some water to the tin to keep the grease from splattering. Place the sholder on the grate away from the coals, add several lumps of apple wood to the fire and cover the grill with upper and lower vents open.
Cook until the internal temperature reaches 180 degrees, approximately 1 ½ hours. Continue to cook the shoulder for 10 minutes after the meat reaches 180 degrees. Pork shoulder is heavily marbled. The high temperature and holding it at 180 degrees allows for most of the fat to render out of the meat and gives you a roast you can slice instead of pulling. A meat thermometer with a probe you can leave in while cooking is highly recommended.
In a bowl combine yogurt, ½ cup minced cilantro, the juice of one lemon, and minced garlic. Season with salt, black pepper and additional lemon juice to taste.
Remove the bacon and slice the shoulder against the grain. Crumble the bacon and offer it as a condiment with the yogurt sauce. Grill the flat bread on each side briefly. Let your guests each make their own sandwich.