Roast chiles over a gas flame, constantly turning so that the skin is charred evenly. Transfer the chiles to a plastic bag and tie closed, allowing the chiles to stem, until cool to the touch. Pull the charred skin off by hand. Once peeled, slice lengthwise removing seeds and veins.
Boil the tomatoes for about 5 minutes. Take off the skin and place into a blender with garlic, onion, salt and pepper, to taste. Pulse until thoroughly combined. Bring to boil over medium heat and keep warm until ready to serve.
Combine the Requezon cheese, chopped pecans and salt and pepper, to taste, in a bowl. Place 1/2 cup of cheese mixture inside each of the chiles, and roll the flesh entirely to close around the cheese. Spread the flour on a plate and dip/roll the chiles in the flour for an even coating. Beat the egg whites until stiff.
Heat the oil to a temperature of about 360 to 375 degrees F.
Dip the chiles in the egg whites, coating evenly. Fry until golden brown. Drain on paper towels. Transfer the chiles to a plate.
To serve, coat the chile in the salsa.