This comes from a dear friend, who was raised on Long Island, and moved to Texas in the 70's.

Skinless chicken breast, about 1 1/2 pounds
1/2 to 2/3 chopped white onion
Enough shortening to sauté onion, 2 or 3 tbls
1 can Cream of Chicken Soup
1 large container of Sour Cream
1/4 to 1/2 cup Milk
Your favorite Picante Sauce (I use Medium Spicy instead of Hot)
Salt and Pepper
Package of Flour Tortillas - Medium Diameter (8" to 9")
Large baking pan, lightly greased
Heat oven to 350°

In a large pot, cover chicken with water, and simmer till done. Drain off broth for other recipes if desired. Allow chicken to cool enough to handle. You need to shred it. I always check for the occasional small bone or tough pieces and toss them away.
In a large bowl, mix soup and sour cream. Add a little milk to thin, you want it the consistency of pancake batter so it may take all the milk or only part of it.
Heat up a Large skillet and add enough shortening to sauté chopped onions. Add onions and a few dashes of salt and pepper. When onions start turning translucent, add 4 or 5 heaping tablespoons of Picante Sauce to skillet. Keep cooking the onions till they are limp. Reduce heat to medium.
When onions are tender, add soup/sour cream mix to skillet, stirring well. Taste. If it's not spicy enough, add more picante, and pepper. This is one of those recipes where you keep tasting till it's right for you. Usually, it's pretty pink from the picante sauce by the time I get it tasting the way I want it.
Don't underestimate the addition of black pepper. You want to see it and taste it!
Add shredded chicken and stir, heat till the chicken is warmed up.
Now for the fun! Spoon about 1/2 cup of the chicken mixture onto half a tortilla. Fold tortilla, tuck ends if you want to Look neat. However no one will ever really see it so I skip the tucking part.
Place enchilada in pan, seam side down. Repeat till pan is full.

You will be covering the enchiladas with the remaining chicken mixture, so be sure to save enough. If it looks as if you're running short, make one less enchilada. And in desperation, add some milk to the mixture to stretch it. Any tortilla not covered will dry out in the oven.
Place baking pan in preheated oven. I always double pan mine so the bottoms of the enchiladas don't over cook. Heat for about 30 minutes, till bubbly and golden on top.
To serve, I cut the enchiladas in half and use a spatula to transfer them to plates. It's easier to do this, than try to serve them at the table. With rice (spanish or white), a salad and refried beans, you have a great meal.
I hope you'll also discover the Pure Joy of eating these cold the next day. They look like heck, but are Wonderful!