Clean the squid thoroughly and cut it into bite-sized pieces.
Thinly slice the onion and green onion.
Heat cooking oil in a pan over medium heat and stir-fry the onion and green onion.
Add the squid and stir-fry together.
Add soy sauce, sugar, and minced garlic, and stir-fry together.
When the squid is cooked, add sesame oil and pepper, then mix well.
Transfer the finished stir-fried squid with soy sauce onto a plate.