Stir fried Beef and Yellow Onion Japanese style

This recipe got inspired by Gyudon-Japanese Beef Bowel without Dashi.

Make 2 servings 

1 Tbs vegetable oil
1/2 medium yellow onion, thickly sliced
2 tsp soy sauce
1 Tbs Sake or white wine like Sherry; etc.
1 Tbs Mirin or Aji Mirin
1 tsp sugar
6 oz beef (rib eye, or tenderloin) thinly sliced
1 green onion, thinly sliced
2 cups of cooked rice.

1. Heating oil in a 10 inch pan over medium high heat.  Add onion, stir until soft.  Add wines; soy sauce, sugar and meat stir well.  Turn the heat down to simmer 2-3 minutes until beef is cooked. 
2. Serve beef over a bowl of rice with some juice.  Sprinkle some green onion.