Heat a large nonstick wok or skillet pan over medium heat.
In a small bowl, whisk together ingredients for sauce and set aside.
Add oil to the pan and then the cubed spam. Cook, stirring occasionally, until spam is caramelized. Remove the spam from the pan and set aside. You can add a little more oil if necessary.
Add the yellow onion, white/light green parts of the green onion, garlic, and carrots to the pan and cook for 2-3 minutes, until carrots are slightly softened. Then, add the green beans and cook for 2-3 minutes, until bright green.
Move all the veggies to one side of the pan and pour the eggs into the exposed side. Allow the eggs to cook completely and then use a wooden spoon to break the egg up into pieces. Add the rice and spam to the pan and mix everything together.
Pour the sauce into the pan and cook, stirring frequently, until the sauce is absorbed into the rice. Season to taste with salt and pepper. Transfer to a serving dish and drizzle with the Japanese mayo and sprinkle with the furikake and the green onion tops.