Roast the fresh poblanos by placing them over an open flame. Turn them in from time to time. Cook until the outer skin is brown, charred, and bubbling.
Place in a plastic bag and let them sweat, for 10 minutes.
When cool remove the outer skin by running your fingers down. Do not wash. Make a small incision and remove the inside seeds by making attention to keep the flesh as intact as possible.
ROASTING THE POBLANO PEPPERS IN THE OVEN METHOD
Line a cookie sheet with aluminum foil, place your peppers, and place under the broiler. Broil for 5 minutes and turn them, and broil for another 5 minutes. remove from the oven, cover with aluminum foil, and let them rest for about 10 minutes.
WORKING THE BATTER, ASSEMBLE AND FRY YOUR CHILES RELLENOS
Once your peppers are cooled off, remove the outer skin. Make a small incision, remove all or some of the seeds, and set them aside.
Fill the inside of the poblanos with the cheese.
Meanwhile, heat oil to a depth of 1 inch.
In a large bowl, beat the egg white until they form soft peaks, but not too stiff and dry. Gradually add the salt and yolks. When they are well incorporated, lights dust one of the chiles with the flour.
Take a perforated spoon or two forks. Dip the chile into the beaten eggs.
Turn it around until it is evenly covered. Make sure the coating is not too thin or too thick. It is useful to have two spatulas or forks to turn the chile around.
Test the oil, should be hot by not smoking, by placing a small amount of batter in the oil. When it sizzles and froths up, the oil is ready.
Lower the chile in the hot oil and turn the chile around. When the batter is well set and has a deep golden color, turn and golden the other side.
Once golden remove from the hot oil and place on a plate with double paper towel to absorb the excess oil.
Combine the cotija cheese and chopped cilantro and sprinkle over it.