Bring a pot of salted water to boil, then add potatoes, cook until tender but still firm to the touch, about 10 minutes.
Drain water and set potatoes aside to cool.
Cook peas and carrots until tender.
When potatoes are cool, add peas and carrots.
Add chopped hard-boiled eggs to potatoes, peas, and carrots.
In a separate bowl add chopped onions, mayonnaise, sour cream, salad dressing or additional mayo mixture, relish, and mix well. Then add to potato mixture.
If after the mayo mixture or salad dressing is added to the potatoes, it still seems a bit dry, repeat with a bit of salad dressing or mayo mixture.
Add Cajun spice, salt, and pepper to taste. Sprinkle with paprika if desired.