Slice the crab: Slice your soft shell tempura crab in half the long way to prepare it for your spider roll.
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 sushi rice. This will prevent the rice from sticking to your hands.
Add sesame seeds: After the rice is pressed onto the nori sheet, add a thin layer of black sesame seeds to the top of the rice. Then flip the sheet over so the rice is facing down.
Flip nori sheet over: Gently flip the nori sheet over so the rice is facing down. You will add the filling directly to the nori sheet with the rice on the outside.
Add the crab: Place both halves of the soft shell crab onto the nori sheet next to each other so the legs are sticking out each end of the sushi. This is what gives the spider roll its signature "spider like" appearance.
Add the masago or tobiko: Spread around a tablespoon of masago (or tobiko) evenly across the nori sheet. This will add a bit of crunchy and salty flavor to your roll.
Cut the avocado and cucumber: Cut the cucumbers into strips that are as long as your nori sheet and about 1/8 inch thick. Then 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 often cut the slices right out of the avocado half and add directly to the roll to ensure freshness. You can also drizzle a little lemon juice over your cut avocado to prevent it from browning in your roll. Add the avocado and cucumber: Add the avocado slices and cucumber sticks horizontally along the nori sheet. In general, I add 2-3 avocado slices and 1-2 cucumber sticks 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's 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 cut each half in half. Then cut each fourth in half. Tip: Be sure to clean and wet the edge of your knife before cutting each roll.
Drizzle with unagi (eel) sauce (optional): I like to lightly drizzle my spider rolls with unagi (eel) sauce prior to serving as I think it provides a good flavor and an appetizing presentation.
Serve and enjoy: I usually serve with unagi (eel) sauce in a ramekin for dipping. You can also serve with soy sauce, wasabi and pickled ginger.