Preheat the smoker to 375F degrees with the lid closed for 15 minutes.
Combine smoked paprika, garlic powder, onion powder, oregano, parsley, black pepper, and cayenne pepper in a small bowl or ramekin and mix. Divide seasoning in half. One will be used for the potatoes and one will be used for the cajun sauce.
In the seasoning bowl for the potatoes add the olive oil and stir. Set aside.
Wash and dry potatoes. Pierce each potato a couple times with a fork. Add to a large mixing bowl and pour in the olive oil spice mixture. Toss to coat.
Cover (with plastic wrap or a clean kitchen towel) and place into the microwave. Cook on high power for 8 minutes.
Remove potatoes from the bowl. Do not discard the leftover olive oil and seasoning, we'll use that in a minute.
Place potatoes onto a foil lined baking sheet. Use a large spoon or the flat bottom of a glass to lightly smash the potatoes. Spoon that leftover cajun olive oil over each potato.
Place tray into the smoker and smoke for 1 hour. Baking sheet should be directly on the grill grates in the center of the smoker. Close the lid and don’t be tempted to peek. This is to ensure the maximum amount of smokey flavor is infused.
Meanwhile, prepare cajun sauce. Combine mayonnaise, heavy cream, cilantro, and cajun seasoning in a small bowl and whisk until smooth. Refrigerate until ready to serve. Add more or less heavy cream depending on sauce consistency preference.
When potatoes are ready, top each potato with chopped red onions. Drizzle with cajun mayonnaise and garnish with a pinch of red pepper flakes and chopped cilantro.