To make the sauce, combine soy sauce, mirin, sake and sugar in a small bowl.
Grate the ginger and add about 1 tsp grated ginger to the sauce. Whisk all together.
Add the thinly sliced pork loin to the sauce and coat the meat well with the sauce. Set aside while you prepare the other ingredients (10-15 minutes of marinate will be good).
Cut the onion into thin slices and cut the cabbage leaves into really thin strips (or shred the cabbage)
Peel the cucumber’s skin alternately to create stripes. Then cut diagonally into thin slices.
Cut the cherry tomatoes in halves. Serve the shredded cabbage, cucumber, and tomatoes on plates.
Heat the cooking oil in a large frying pan over medium heat. Add the sliced onion.
Saute the onion until it’s translucent, about 3 minutes. Move the onion to the side of the pan to create a space for the meat.
Add the marinated pork and cook for 4-5 minutes. Help the pork slices separated so they will cook evenly.
When the meat is no longer pink, drizzle a little bit of soy sauce and give a quick stir. Serve immediately.