Prepare the sushi rice by folding rice vinegar and sea salt into the warm, cooked rice until well combined and glossy.
Slice the sashimi-grade salmon and ahi tuna into long, thin strips approximately half an inch thick.
Julienne the cucumber into thin matchsticks and slice the avocado into long, slender wedges.
Place a nori sheet on a bamboo rolling mat and spread half of the rice evenly over the bottom two-thirds of the sheet.
Layer half of the salmon, tuna, avocado, and cucumber across the center of the rice bed.
Carefully roll the nori tightly from the bottom, using the mat to guide the shape, and seal the edge with a small drop of water.
Repeat the process with the second nori sheet and the remaining ingredients.
Slice each roll into eight uniform pieces using a very sharp, wet knife to ensure clean cuts.
Serve immediately with coconut aminos, wasabi, and pickled ginger on the side.