Combine first six ingredients and set aside.
In a wok or large skillet, heat oil over medium heat until shimmering.
Add the Spam and cook until crispy. Remove and set aside.
Add the onion and saute until translucent.
Add garlic and cook until fragrant.
Add frozen vegetables and cook a few more minutes until cooked through.
Push the vegetables to the side and add butter. Add beaten eggs to the melted butter. Scramble the eggs and mix them with the vegetables.
Add the cooked rice and break apart.
Add sauce and cook until thickened and absorbed, while mixing.
Serve with a drizzle of Yum Yum sauce and/or Kewpie mayo over the top. Garnish with sliced green onions.