NOTE: The pork and cheese mixture is enough to stuff 8 poblano peppers. Simply increase your peppers, flour, and egg according to how many peppers you will be stuffing. I usually just stuff 2 peppers and then we just eat the leftover stuffing in tacos but sometimes stuff 8 peppers if having guests.
Roast your peppers on a foil-lined baking sheet at 425 degrees F for 20 minutes or until their skins start to blister and char a little bit. Turn them over halfway through.
Put the peppers into a ziploc bag and keep it sealed for about 30 minutes to allow the peppers to "sweat".
Meanwhile, cook your pork in a skillet until no longer pink then drain it and place in a mixing bowl.
Put your cheese in with the hot pork and mix it around, allowing it to melt a little with the meat.
After the 30 minutes, carefully remove the skins on your poblanos. (As much as you can without tearing up the pepper--it's o.k. if a little stays on.
In the foil where your peppers were, spread out your flour.
Cut a "T" shape (top of the "T" being at the stem of the pepper) into your peppers carefully and remove the seeds then lay them into the flour on their outsides.
Put a little of the pork and cheese mixture into the pepper, sprinkle with tomatoes then close the pepper up and secure it with a toothpick.
Beat the egg white in a medium bowl until stiff. Beat the egg yolk lightly in a small bowl then fold into the egg white and gently fold them together.
Pour oil about 1/4 inch deep into a large frying pan. Heat the oil to about 365 degrees F. (doesn't have to be exact, just hot).
Dip the stuffed, floured peppers carefully into the egg mixture to coat then lay them gently into the hot oil.
Fry until golden brown and then turn with a spatula to brown the other side.
Remove to a plate and serve with your favorite queso sauce or salsa!