In a medium mixing bowl, combine one can of drained tuna, mayonnaise, celery, and green onions. Add lemon juice, salt, and pepper; mix until well combined.

Lay out a nori sheet shiny side down on a clean flat surface. Have a small bowl of water nearby.

Spoon a portion of the prepared tuna salad into the center of the nori sheet, leaving an inch from the edges.

Starting from the edge closest to you, roll the nori tightly over the filling, tucking it gently as you go, sealing with a bit of water.

Slice the roll into bite-sized pieces and serve immediately, or chill until ready.