Preheat the oven: Set oven to 400°F (200°C). Line a baking sheet with parchment paper or lightly grease with oil.
Prepare the spice rub: In a small bowl, mix garlic powder, onion powder, paprika, oregano, cayenne, salt, and black pepper.
Season the salmon: Pat salmon fillets dry with paper towels. Brush with olive oil on both sides, then coat generously with the spice blend.
Bake the salmon: Place fillets on the prepared baking sheet. Bake for 15–18 minutes, or until salmon flakes easily with a fork and reaches an internal temperature of 145°F (63°C).
Finish with lemon: Remove salmon from the oven, squeeze fresh lemon juice over the top, and garnish with parsley.
Serve: Plate with lemon slices on the side and enjoy hot.