Preheat your oven to 350°F (175°C) and line a large baking dish or rimmed baking sheet with a large piece of aluminum foil.
Place room temperature salmon on aluminum foil. Drizzle the salmon with olive oil and brush with so that the salmon is coated evenly. Sprinkle with cajun seasoning and additional salt if desired and coat evenly. Sprinkle the zest of lemon over seasoned salmon.
Fold the sides of the aluminum foil up and over the top of the salmon until it is completely enclosed. If your piece of foil is not large enough, place a second piece on top to form a sealed packet. Leave a little room inside the foil for air to circulate.
Bake the salmon for 15-20 minutes, until the salmon is completely cooked through at the thickest part. The cooking time will vary based on the thickness of your salmon and your oven.
Open foil packet and serve immediately. Top with parsley and additional lemon slices.
