In a measuring cup or bowl, combine soy sauce, mirin, sugar, and water. Mix well.

Spray a pan with oil and pan-fry the pork slices for 4 to 5 minutes, or until golden brown.

Add sliced onions and garlic to the pan. Toss and cook for 2 minutes.

Pour in the prepared sauce. Let the pork absorb the flavors and allow the sauce to thicken for about 2 minutes.

Serve the cooked pork and onions over a hot bowl of rice.

Drizzle with any remaining sauce and garnish with green onions, sliced cucumbers, and sesame seeds before serving.