Mix the salt, chili powder, cumin, paprika, onion and black pepper together, rub the salmon fillets with olive oil and this seasoning mix.
Refrigerate for at least 30 minutes.
Pre-heat the grill.
Combine the avocado, onion, cilantro, lime juice, and salt in a bowl and mix well, chill until ready to use.
Grill the salmon to desired doneness. (I grilled for about 5 minutes)
Top with avocado salsa and enjoy!