Put flour in a pan and lightly roast. Add butter. Mix well.
Add water. Mix well.
Stir fry olive oil, onion, garlic, beef and favorite mushroom in another pan. Until you like it.
Add number 2 and tomato paste, Worcestershire sauce. Mix well while heating.
Add sour cream. Mix well while heating.
Adjust the taste with salt and pepper.Finish.
Notes
This recipe has a slightly stronger taste. Because it is for Bento(Japanese lunch box).Bento↓↓↓In order to eat deliciously even in the cold state, it is usually a little stronger.