Slice the avocado in half, remove the pit and scoop out the insides into a small bowl. Add in the tuna, celery, lemon juice, and salt (plus green onion and cilantro if using) and use the back of a fork to mash together. Gently fold in the tomato then scoop the mixture back into the avocado shells. Sprinkle with hemp hearts. Alternatively you could make it into a sandwich with whole grain or gluten free bread.
Recipe by Love from the Land at https://www.lovefromtheland.com/tuna-avocado-cups/