Preheat oven to 400℉. Place the salmon in a parchment-lined 9 x 13-inch pan. Sprinkle with salt and pepper and smear with the olive oil. Cover the salmon with parchment paper and then with silver foil. This method will “poach” the fish.
Bake for about 30 minutes, until salmon is cooked through (a larger side of salmon might need more time).
To assemble, place the sushi rice on a platter. Top with the cooked salmon, using a wide spatula or fish spatula to help you transfer the salmon from the baking pan to the platter.
Top with cucumber, mango, carrot and avocado. Sprinkle with the onions and then drizzle the sauces to your liking.