Fill a large pot about 2/3 full with water. Add salt and chopped onions. Bring to a boil and cook while preparing the potatoes.
Peel potatoes and cut into chunks.
Once onions are tender, add the potatoes to the boiling water. Return to a boil, reduce heat and simmer until potatoes are fork tender but still slightly firm.
Once potatoes are done, drain and return to pot. Make sure all onions make it back into the pot.
Chop eggs and add to potatoes along with the relishes, Miracle Whip a, pepper and mustard. Stir together. It should be creamy. If not, add a little more miracle whip.
*The onions take longer to cook than the potatoes. But by cooking them like this, you still get the onion flavor but not the crunch. Lots of people in my family don't like the crunch (mostly kids). Doing it this way, they don't even realize there are onions in it. I've converted several potato salad haters.