Prepare rice according to package directions. Stir in vinegar and salt; cool.
Cut off the top quarter of nori sheets along short end. Place 1 nori sheet, shiny side down, on a sushi mat covered with plastic wrap, with long end toward you. Pat 1 cup rice over nori with moist hands, leaving a 1-inch border on one long end of nori.
Arrange 2 avocado slices, 2 carrot strips, 2 cucumber strips, and 2 crab halves along the top third of the rice-covered nori.
Lift edge of nori closest to you; fold over filling. Lift bottom edge of sushi mat; roll toward top edge, pressing firmly on sushi roll. Continue rolling to top edge; press mat to seal sushi roll. Let rest, seam side down, 5 minutes. Slice crosswise into 8 pieces. Repeat procedure with remaining nori, rice, avocado, carrot, cucumber, and crab sticks.