Add minced pork, ginger and Shaoxing wine into a large bowl. Mix well.
Add sweet bean sauce to a medium sized bowl. Slowly blend in water and stir constantly, until water is fully incorporated.
Heat a wok (or a heavy bottomed skillet) over medium high heat. Add oil and wait until oil is hot, 2 to 3 minutes. Add pork and stir constantly, until the surface turns mostly white. Swirl in sweet bean sauce. Turn to medium heat and keep stirring constantly, until the sauce turns almost black, about 10 mins. If the sauce thickens too quickly and starts to feel like it's sticking to the bottom of the wok, slowly blend in warm water, 1/2 cup at a time. Reduce the heat if the wok gets too hot.
Add onion into the sauce and keep stirring, until fully cooked but still crisp, 3 to 5 minutes. Stop heat and transfer the sauce to a large bowl.
Bring a large pot of water to a boil and cook noodles according to instructions.
Add noodles to serving bowls. Top noodles with sauce, cucumber, and stir fried tomato and egg.
Serve warm.