Pat the salmon fillets dry with a paper towel. Mix together Cajun seasoning, olive oil, lemon juice, garlic powder, smoked paprika, salt, and black pepper in a bowl. Rub this blend onto the salmon fillets and let marinate for about 15 minutes.

Heat a skillet over medium-high heat and add olive oil. Place the marinated salmon fillets skin-side down in the skillet, sear for 4-5 minutes, then flip and cook for another 3-4 minutes until cooked through.

In a blender, combine ripe avocados, sour cream (or Greek yogurt), lime juice, cilantro, garlic, and cayenne pepper. Process until smooth, adding water gradually to reach the desired consistency.

Prepare rice according to package directions. Warm tortillas if using.

Assemble the dish by serving salmon on rice or in tortillas, topping with avocado-lime crema and any desired toppings.