Cut the avocado and cucumber: First, slice the avocado in half the long way. Remove the seed and cut each half into 6 slices. Each whole avocado should yield around 12 slices. I would also drizzle lemon juice over the avocado after cutting to prevent it from browning in your sushi roll. Finally, cut the cucumbers into strips that are as long as your nori wrapper and about 1/8 inch thick. Prepare your bamboo sushi mat: Cover your bamboo sushi mat with plastic wrap. This will help keep the rice from sticking to it.
Press rice onto nori sheets: Next, place the nori sheet onto the plastic wrap with the shiny side facing down. Then press around 1 cup of rice onto the nori sheet in an even layer. Tip: Wet your hands prior to handling the rice to prevent the rice from sticking to your hands.
Add tobiko or masago: After the rice is pressed onto the nori sheet, add a thin layer of tobiko or masago to the top of the rice. Then flip the sheet over so the rice is facing down.
Add the filling: Add the avocado slices, shrimp and cucumber sticks horizontally along the nori sheet. In general, I add 2-3 avocado slices, 1-2 cucumber sticks, and 4-5 pieces of shrimp depending on the size of each ingredient and how everything fits.
Roll the sushi: Use the bamboo sushi mat to fold your roll until it is completely enclosed. Once the rice is making contact with the nori roll, pull back the sushi mat so it doesn't get caught in the sushi. Still using the sushi mat as your guide, finish rolling until the roll is completely wrapped. Then wrap the sushi mat around the roll and gently press, tightening the roll together.Keep in mind that rolling sushi is an art that may take some practice so don’t get frustrated if it doesn’t look perfect your first time. It will get easier the more you do it. Cut the roll: Using a sharp knife, cut the roll into 8 pieces. I do this by first cutting the roll in half. Then cutting each half in half. Then cutting each fourth in half. Tip: Be sure to clean and wet the edge of your knife before cutting each roll.
Serve and enjoy: I usually serve with soy sauce and wasabi. Sushi rolls are traditionally served with pickled ginger, gari, as well.