Preheat your oven to 400°F (200°C).
In a medium-sized bowl, combine the Cajun seasoning, olive oil, and lemon juice. Stir until a smooth paste forms.
Place the salmon fillets on a baking sheet lined with parchment paper and rub the Cajun mixture over each fillet.
Bake the salmon in the preheated oven for about 15-20 minutes, until it flakes easily with a fork.
Dice the avocado and toss it with salt, pepper, and a squeeze of lemon juice.
Let the salmon rest for a couple of minutes after baking.
Serve the salmon topped with the avocado mixture and garnish with fresh cilantro.