My aunt Norma taught me how to make this recipe when I was about 16 years old, one of the first recipes I ever mastered. They taste just like the ones I grew up eating at various Mexican restaurants around Southern California in the 50's and 60's. Most of all I remember Mitla's on Mt. Vernon Ave., in San Bernardino, CA, every time I make these I remember Tuesday dinners with the family at Mitla's, the #2 combo plate, Taco, Chile Relleno, Cheese enchilada with rice and beans, the best in the West!
If using fresh, skins must be removed, I deep fry until skins are brown and chile is cooked. Do not remove stem or seeds. Plunge into cold or ice water, skins will come off easier if you start at the tip and peel towards stem. If using canned, wash, remove seeds, and pat chiles dry. Keeping them whole. Cut enough Xoaca or Jack cheese into strips to stuff each chile, and set aside. Grate whatever cheese you don't use to stuff the chiles, and save it with the shredded cheddar to sprinkle over chiles when they are done.
Beat egg whites until stiff. Add salt to yolks and stir in the flour, it will be very stiff and pasty, add water enough to make smooth but thick. Fold into stiff egg whites. It will be a very nice thick batter. (Sometimes I will add salsa juice instead of water to thin out the yolk mixture. For a less "eggy taste", I will use a 2 whites to one yolk ratio, if you have more chiles you will need to use more eggs, don't stress it's hard to mess it up.)
Heat oil in skillet, on my electric range I do it on medium, a little on the high side. I use the oil from the deep fryer, that I used to cook the chiles to get the skins off. It makes a better tasting pepper in the end.
When oil is hot, hold by stem (if fresh) dip stuffed chiles into batter, and drop gently into hot skillet. Cook until golden brown, (they will try to float) turn and do the same on the other side. Remove from oil. I place on paper towels or on a rack over them, to drain, sprinkle with cheese. (You can deep fry them and they are delicious that way also, but I prefer pan fried.)
I like to serve with either salsa over the chile or some chile verde spooned over it. I like to put one in my burrito too.