Season the cooked brown rice with rice vinegar and sea salt in a small bowl until well combined.
Place one nori sheet on a bamboo rolling mat or a clean, flat surface with the rough side facing up.
Spread half of the seasoned rice in a thin, even layer over the nori, leaving a one-inch border at the top edge.
Arrange half of the cooked shrimp, smoked salmon, avocado, cucumber, and carrots in a horizontal line across the center of the rice.
Carefully roll the nori from the bottom edge upward, using the mat to maintain a firm, tight cylinder.
Repeat the assembly process for the second nori sheet with the remaining ingredients.
Use a very sharp, wet knife to slice each roll into six even pieces to prevent tearing the seaweed.
Garnish the rolls with sesame seeds and black pepper, then serve immediately with coconut aminos for dipping.