Soften flour tortillas in a warm oven or in a microwave. This makes them easier to handle. I soften one tortilla at a time, build a relleno, and then warm another tortilla. If you warm them all at once, the last onces may get hard before you can roll them.
Lay tortilla on flat surface, place 1/2 cup cheese in center of tortilla and place 1/4 to 1/2 can of chilies on top of cheese. Fold bottom of tortilla over the cheese/chilies (away from you), then hold that while you fold in both sides. Finally, fold top side of pouch back over the center and close by securing with a toothpick or two. This will need to hold the relleno closed while it's baking or frying (if it's loose, the insides will leak out). Repeat with the other tortillas until you have used all four.
Place rellenos in deep fryer and fry for approximately 4 minutes on a fairly hot setting. If you don't have a deep fryer, place in a cast iron or other heavy skillet that has about 1 inch or so of oil in it, heated to a medium-hot setting. Fry on each side for about 2 minutes or until golden brown and the cheese in the center has had a chance to melt. If you don't want to fry, place rellenos on a baking sheet and bake in a hot oven (380 degrees F) for about 10 minutes (or until golden brown).
While rellenos are cooking, heat salsa just until warm in small sauce pan over medium heat or about 1 minute in a microwave (on full power).
If you fried the rellenos, drain on paper towels. If you baked them, go to the straight to the plate! Place chili rellenos in the center of a plate, remove all toothpicks, and cover each relleno in about half a cup of warm salsa. Serve immediately.
They should be crunchy on the outside with warm melted cheese and chilies on the inside. Serve with refried beans, Mexican rice, warm tortilla chips, and a side salad.