Place one sheet of seaweed, shiny side down, on your bamboo sushi rolling mat.
Gently spread a thin layer of sushi rice on top, leaving about the top inch of seaweed empty.
Place a thin layer of avocado (or other filling) on top of the rice along the bottom edge of the sushi mat.
Continue layering your filling in very small amounts, placing them on top of each other. Your fillings should not take up more than 1-1.5 inches of space on your sushi mat.
Roll your sushi, starting from the edge with the fillings. I find it helps to put my thumbs under the bamboo mat with the rest of my fingers holding my fillings in place for that initial roll.
Gently squeeze the bamboo mat into a cylinder shape as you roll along.
Repeat with the remaining seaweed sheets and sushi fillings, and serve the ehoumaki uncut. Leftover sushi filling can be kept in the refrigerator, but sushi rice does not save well.