Slice the zucchini into half-moon shapes.
Chop the onion and green onion finely.
Drain the oil from the canned tuna using a strainer.
Heat cooking oil in a pan and stir-fry the green onion to release its aroma.
Add the onion and zucchini and stir-fry together.
Add the tuna and stir-fry, mixing well.
Season with soy sauce and salt to taste.
Finish by adding sesame oil and turn off the heat.