In a small bowl, gently fold the rice vinegar and sea salt into the warm cooked sushi rice, then set aside to cool to room temperature.
Slice the sushi-grade ahi tuna into long, thin strips and ensure the cooked shrimp are peeled, deveined, and tails removed.
Julienne the cucumber into thin matchsticks, shred the carrots, and thinly slice the avocado.
Place one sheet of nori on a bamboo rolling mat and spread half of the seasoned rice in a thin, even layer, leaving one inch of the top edge clear.
Arrange half of the tuna, shrimp, avocado, cucumber, and carrots in a horizontal line across the center of the rice.
Using the mat, roll the nori tightly from the bottom upward, moistening the top edge with a drop of water to seal the roll.
Repeat the process for the second roll, then use a very sharp, wet knife to slice each roll into six to eight even pieces.
Serve the fresh rolls immediately with coconut aminos for dipping and a small dollop of wasabi paste for heat.