Place all the Cajun seasoning ingredients in a small bowl and whisk until well combined. Set aside.
Cut the potatoes into 1-inch pieces and place into a large pot.
Cover the potatoes with about 2 inches of water and bring the water to a boil.
Once the water is boiling, add the eggs to the pot straight from the refrigerator and set a timer for 10 minutes.
Meanwhile, prepare a bowl of ice water.
After 10 minutes, remove the eggs from the pot and place them in the ice bath to cool for about 10 minutes.
Cook the potatoes for about 10-12 more minutes until very soft, then drain them, return them to the pot, and set the pot aside to cool slightly.
When the eggs are cool, drain them and peel them.
Separate the egg whites and yolks.
Chop the egg whites into pieces about ¼-inch long and set them aside.
Place the yolks in a mixing bowl and add the reserved Cajun seasoning along with the mayonnaise, mustard, relish, salt, and black pepper.
Mash the mixture with a fork until well combined.
Add the celery, onion, and bell pepper and stir until evenly distributed.
Mash the potatoes with a potato masher, leaving some chunks for texture.
Add the egg yolk mixture to the potatoes and stir until the potatoes are creamy.
Add the chopped egg whites and stir carefully until evenly distributed. Taste and adjust for salt and black pepper. You can add more mayonnaise if you like it creamier.
Garnish the potato salad with sliced scallions and a sprinkle of paprika. Serve warm or at room temperature. Refrigerate leftovers up to 3-4 days and bring to room temperature before serving.