Cook onions a couple of handfuls at a time, stirring constantly
Slowly stir in the rest of the onion by handfuls until you've added them all.
Season with kosher salt.
Reduce heat to medium low and continue stirring for approximately 15 to 20 minutes or until the onion is cooked to desired "doneness". A soft yellow look is great for French onion look while browner more caramelized onions are perfect for topping off sandwiches, etc.
If the onions are sticking to the pan, add a bit of broth or water and continue stirring.
Let cool in the pan.
Notes
Use the caramelized onions to top off mashed potatoes, chicken or steak on sandwiches, pizzas, etc.
I usually double this recipe I love it so much and they store in the refrigerator well for about 5 days.