Keep the filling ingredients ready. Cook and prepare the sushi rice, boil shrimp for 5 mins, cut cucumber lengthwise and cut avocado into smaller slices.
Cut nori seaweed into two. We will only need ½.
Spread most of the rice (reserve about 2-3 tablespoon) over one side of the nori seaweed. Stick it to the nori sheet so that it's all an even layer.
Turn the sheet with the rice around and spread the remaining 2-3 Tablespoons of rice over the inside part of the nori sheet too. Keep a ½ to 1 inch or 1 to 2 cm border where you don't add rice to the top and the bottom only.
Add the mayo in a line over the rice, place shrimp, cucumber, and avocado slices over the rice so that everything fits. If you need to cut a bit of cucumber or avocado, that's ok. As long as everything is spread out equally.
Start to roll in your sushi with the help of your bamboo mat. Gently roll and press down with both your hands until you have a tight sushi roll.
Cut your avocado half into thin slices. It helps if you have a sharp knife.
Place avocado slices over the sushi roll so that they are spread out a bit. That way the avocado looks like green dragon scales.
Place a cling wrap over the avocado and the sushi mat and wrap around the avocado so that it sticks on the inside-out sushi rice. The avocado slices should be holding to the rice on the sushi roll.
Slice your sushi roll with a sharp clean knife into 8 slices. It helps if you clean and wet your knife after every cut.
Top with tobiko fish roe if you like and serve up.