In a small bowl, whisk together 2 tablespoons olive oil, minced garlic, chili powder, cumin, onion powder, black pepper, and salt. Brush or rub this spice mixture over both sides of the salmon fillets. Use immediately or marinate in refrigerator for up to 2 hours.

Heat a large heavy-duty non-stick pan or grill to medium-high heat (375-400°F) and add a light drizzle of olive oil. Place salmon fillets in the pan and cook without moving for 5-6 minutes until a golden crust forms and edges look opaque.

Carefully flip the salmon using a wide spatula and cook for another 5-6 minutes until the fish flakes easily with a fork and reaches 145°F internal temperature. The flesh should look opaque with slightly darker pink center. Remove from heat when almost done as it continues cooking.

While salmon cooks, combine diced avocado, tomato, onion, and cilantro in a large bowl. Drizzle with 1 tablespoon olive oil and lime juice. Season with salt and pepper. Gently fold together with a spoon, being careful not to mash the avocado.

Let cooked salmon rest for 1-2 minutes, then top each fillet generously with avocado salsa. Serve immediately.