Cook rice as directed on package. You will need 1 cup cooked rice for this recipe; place remaining rice into a ziplock bag and freeze for future use.

Cut cucumber into 1 inch slices and then cut out the seeds. If you have a round cookie cutter or melon baller, this will make it easier.

Mix 1 cup cooked rice with avocado, mayonnaise, lemon juice, and drained tuna.

Fill each cucumber with tuna mixture and serve. Store any unused sushi in a sealed container in the fridge.