True to its name, this rolled sushi was invented in California by an enterprising Japanese sushi chef in the early 1970s.

Step 1: Encase mat in plastic

Cut a large piece of plastic wrap a little more than twice the size of your bamboo mat and place it on the table. Place the bamboo mat on top and encase it in the plastic by smoothing the wrap evenly over both sides. Set the mat aside.

Step 2: Prepare cucumber

Peel the cucumber and scoop out the seeds with a small spoon. Cut the cucumber half into thin strips about 1/8 – to 1/4-inch wide and set them aside.

Step 3: Prepare avocado

Cut the avocado in half lengthwise and twist the two halves until they separate. Cut the half without the pit into two quarters. Remove their skin and cut them lengthwise into quarter-inch slices. Set the slices aside and clean your hands and knife with the damp kitchen cloth.

Step 4: Put rice on nori

Lay a half sheet of nori shiny side down. Moisten your hands with a little water and grab a handful, or about a cup, of prepared sushi rice. Ball it up and put it on top of the nori.

Step 5: Spread rice

Spread and pat the rice across the nori, leaving a 1/2-inch margin uncovered at the bottom edge.

Step 6: Sprinkle sesame seeds

Sprinkle sesame seeds over the rice.

Step 7: Flip nori onto mat

Lay the plastic-wrapped bamboo in front of you. Flip the prepared nori sheet rice-side down at the bottom end of the mat.

Step 8: Lay filling in nori

Lay a strip of shredded crab across the middle of the nori, add a strip or two of cucumber next to it, and lay avocado slices on top.

Step 9: Roll with mat

Use the bamboo mat to roll the bottom edge of the nori over the filling in the center, tucking it over firmly so the filling is enclosed.

Step 10: Continue to roll

Pull the mat back and lay it over the roll again. This time continue to roll forward, applying even pressure and tightening as you roll, using your mat as leverage.

Step 11: Smooth out roll

Once it’s taken shape, take the roll off the mat and lay the mat over it. Press and smooth the roll, compressing it tightly and evening out the ends.

Step 12: Cut roll

With a very sharp knife use a delicate but firm sawing motion to cut the roll in half. Cut each half into three equal pieces.

Step 13: Repeat process

Repeat the process with your remaining half of nori, lightly layering it with rice, adding the filling, and rolling and cutting the sushi. Eat at your leisure—after all, this is California-style.