Lay salmon skin side down on a 13 by 9-inch baking dish. In a small bowl, whisk together the soy sauce, Dijon mustard, garlic and olive oil. Pour the marinade over the salmon, reserving 2 tablespoons.

While the salmon rests in the marinade, make the avocado salsa by combining the avocado, red onion, lime juice, and cilantro in a small bowl.

Preheat grill and brush grates with oil. Place salmon on the grill skin side down and cook 4-5 minutes, then flip and cook another 4-5 minutes until it reaches desired doneness.

Remove the skin from the salmon then drizzle remaining 2 Tbsp of the marinade over salmon, and spoon the desired amount of avocado salsa on top.

Serve and enjoy!