Prepare the sushi rice by seasoning the cooked rice with rice vinegar and a pinch of sea salt, then let it cool to room temperature.
Slice the sashimi-grade salmon into long, thin strips approximately half an inch thick.
Peel and slice the avocado and cucumber into thin matchsticks.
Place one sheet of nori on a bamboo rolling mat, shiny side down.
Wet your fingers and spread half of the rice in a very thin layer over the bottom two-thirds of the nori.
Arrange half of the salmon, avocado, and cucumber strips in a horizontal line across the center of the rice.
Carefully lift the edge of the mat and roll the nori tightly over the fillings, using a drop of water to seal the edge.
Repeat with the second nori sheet and remaining ingredients.
Use a sharp, damp knife to slice each roll into six even pieces.
Serve immediately with coconut aminos, wasabi paste, and pickled ginger.