Cut the chicken into bite-sized pieces.
Julienne the onion and carrot.
Heat cooking oil in a pan and stir-fry the chicken.
When the chicken is halfway cooked, add the vegetables and stir-fry together.
Add ketchup, soy sauce, and sugar, and stir well while cooking.
Add tomatoes and eggs, and quickly mix them.
Continue stir-frying until everything is cooked through.
Finally, add green onions and give it one last stir to finish.