Finely chop the Spam and onion.
Heat oil in a pan and stir-fry the Spam and onion.
Add soy sauce, sugar, and cooking wine, and stir-fry to season.
Place cooked rice in a bowl and top with the fried Spam mixture.
Drizzle mayonnaise and sprinkle with pepper.
Add chopped green onions and a fried egg as desired.