Cook the Rice: In a medium saucepan, bring the water and salt to a boil.
Add the rice, reduce the heat to low, cover, and simmer for 20 minutes or until all the water is absorbed.
Season the Rice: In a small bowl, stir the rice vinegar and sugar together until the sugar dissolves.
Drizzle this mixture over the hot cooked rice and gently fluff with a fork to combine.
Set aside to cool completely.
Prepare Your Station: Place your bamboo sushi mat on a clean, flat surface so the strips are horizontal to you.
Arrange all your prepared filling nearby for easy access.
Assemble the Roll: Lay one sheet of nori on the mat. Scoop about 3/4 cup (960 ml) of the cooled rice onto the nori. Wet your fingers and gently press the rice into an even layer, leaving a 1-inch (2. 5 cm) border clear at the top edge.
Add the Fillings: Spread 1 tablespoon (15 ml / 0.5 fl oz) of mayonnaise in a horizontal line across the center of the rice.
Layer one-third of the carrots, avocado slices, cucumber sticks, lettuce, and pickled ginger on top of the mayonnaise.
Roll the Sushi: Dip your finger in water and moisten the bare top edge of the nori.
Using the bamboo mat to help you, lift the bottom edge of the nori up and over the filling, tucking it in snugly.
Continue to roll forward, applying gentle, even pressure, until the roll is sealed.
Repeat to make three rolls.
Slice and Serve: Place a roll seam-side down on a cutting board.
Using a very sharp, wet knife, trim the ends and then slice the roll into 8 equal pieces.
Arrange the pieces on a platter.
Prepare Garnishes: In a small bowl, mix the wasabi powder with the water to form a smooth paste.
Serve the sushi immediately with the wasabi paste, pickled ginger, and a small bowl of tamari for dipping.
Keep a small bowl of water handy to dip your fingers in. This prevents the sticky rice from clinging to your hands while spreading it on the nori.
Don't overfill your rolls. It's tempting, but a thinner layer of fillings makes the roll tighter, neater, and less likely to fall apart.
