Wash and peel the cucumber, then slice it lengthwise into thin strips.
Use a spoon to scoop out the seeds, creating a hollow tube.
Prepare your fillings by slicing the fish, avocado, and carrot into thin strips.
Carefully stuff the cucumber tubes with fish, avocado, and carrot.
Sprinkle sesame seeds inside for added flavor.
Cut the cucumber rolls into bite-sized pieces with a sharp knife.
Arrange the sushi on a plate.
Serve with soy sauce, wasabi, and pickled ginger on the side.
Enjoy immediately for the freshest taste.
Experiment with different fillings as desired!