Bring a medium pot of water to a boil. Add the udon noodles and cook for 1 minute until they are just separated. Do not cook for longer or else they will be mushy. Remove from water and set aside.
In a small bowl, add the eggs, white pepper, shaoxing wine, and 1 tablespoon of water. Mix until thoroughly combined.
Heat one tablespoon of oil over medium-high heat in a nonstick pan*. Add the eggs and scramble them quickly then remove to a bowl.
In the same pan, add the remaining two tablespoons of oil. Increase the heat to high, add the tomatoes and fry for 2 minutes.
Add the ketchup, sugar, chicken bouillon powder, MSG, and water. Cook for 2-3 minutes.
Add the udon noodles and scallions and toss to combine. Cook for 1 minute until the sauce is slightly thickened and coats the noodles.
Notes
*The reason I use a nonstick pan over a wok is because the acid in the tomato sauce causes the wok's seasoning to dissolve which I don't like.