Preheat the oven to 400 degrees F and grease a large baking sheet.
Arrange the salmon fillets on the baking sheet.
In a small bowl, stir together the oil, salt, pepper, garlic, oregano, and juice of ½ lemon.
Spoon the mixture over the salmon fillets.
(Be sure to rub all over the sides of the salmon as well so it has no dry spots).
Thinly slice the remaining ½ of lemon and top each piece of salmon with a slice of lemon.
Bake for 12-15 minutes until the salmon is opaque and flaky when pulled apart with a fork.
You can broil the last 1-2 minutes, if desired, for a browner color.
Meanwhile, mix all the avocado pico de gallo ingredients in a small bowl.
Once the salmon is ready, serve the fish on a plate.
Add a generous spoonful of the avocado pico de gallo to the top of the fish and enjoy!