Slice the cucumber in half lengthwise. Scoop out the seeds with a spoon to create shallow boats, then pat dry.
Spoon sushi rice into each cucumber half, pressing gently to form an even base.
Layer smoked salmon evenly over the rice.
Top with teriyaki sauce, sesame oil (if using), sesame seeds, and green onions.
Slice into bite-sized pieces or enjoy whole as sushi boats. Serve with soy sauce or spicy mayo on the side.
