Stir the rice vinegar and sea salt into the warm cooked sushi rice until well combined.
Slice the sushi-grade salmon, cucumber, and avocado into long, thin matchsticks.
Place one nori sheet on a bamboo rolling mat and spread half of the rice in a thin, even layer, leaving the top inch clear.
Arrange half of the salmon, shrimp, cucumber, and avocado in a horizontal line across the center of the rice.
Carefully roll the nori from the bottom up, using the mat to maintain a tight, cylindrical shape.
Dampen the top edge of the nori with a tiny bit of water to seal the roll completely.
Repeat with the second nori sheet and remaining ingredients, then slice each roll into eight pieces with a sharp, wet knife.
Serve the fresh rolls immediately with coconut aminos, wasabi, and pickled ginger for dipping.