Crack the eggs into a bowl and season lightly with MSG or salt. Whisk until well combined.
Heat a pan over medium heat and drizzle in a little oil. Pour in the eggs and cook until about 70% set—soft and slightly runny in places. Remove from the pan and set aside.
Add a bit more oil to the same pan. Sauté the garlic and the white parts of the green onion until fragrant, about 30 seconds.
Add the tomatoes and water. Cook until the tomatoes soften and release their juices, forming a light sauce.
Stir in oyster sauce, ketchup, sugar, and a pinch of MSG or salt. Mix well and let the sauce simmer for 1–2 minutes.
Return the eggs to the pan. Gently fold everything together until the eggs are coated in the tomato sauce.
Add the green parts of the green onion and give a final stir.
Serve hot with steamed rice.