Start by gathering all your ingredients and preheating your oven to 300°F (150°C).
In a medium-sized pot, bring the water to a rolling boil, then add the rice. Lower the heat to medium-low, cover the pot, and let the rice simmer until fully cooked and all the water is absorbed, about 20 to 25 minutes.
While the rice is cooking, combine the rice vinegar, sugar, and salt in a small bowl. Once the rice is done, gently mix the vinegar mixture into the warm rice, ensuring the grains are well-coated. Set aside to cool slightly.
Place the nori sheets on a baking sheet, and warm them in the preheated oven for 1 to 2 minutes.
Lay one sheet of nori on a bamboo sushi mat. With dampened hands, spread a thin, even layer of rice across the surface of the nori.
Along the center of the rice, arrange a portion of the crabmeat, avocado slices, cucumber strips, and pickled ginger.
Starting from one edge, use the sushi mat to tightly roll the nori over the filling, forming a compact sushi roll. Repeat the process with the remaining nori sheets and ingredients.
Finally, with a wet, sharp knife, slice each roll into 4 to 6 even pieces. Serve and enjoy!