Slice the onion and mushrooms. Remove the core of the onion and cut into thin slices. Slice mushrooms into 5mm thickness.

Season the beef with salt and pepper, then coat with flour.

Heat vegetable oil in a pan over medium heat. Add the onion and sauté until softened. Add the beef and cook until its color changes, then add mushrooms and stir-fry together.

Add red wine and cook for about 1 minute to evaporate the alcohol. Add demi-glace sauce and simmer on low heat for 7–8 minutes until thickened. Season with salt and black pepper.

Mix cooked rice with butter in a bowl to prepare butter rice.