Mince the onion and microwave with 1 tsp salad oil for 1 minute at 600W. Slice mushrooms and prepare shimeji mushrooms.

Combine breadcrumbs and milk in a bowl. Add ground meat, onion, and seasonings, mixing until sticky.

Divide the mixture into two portions, shaping into oval patties.

Heat 1 tsp salad oil in a pan and cook patties until browned on both sides. Cover and cook on low heat for 7 minutes.

In a clean pan, melt butter and sauté mushrooms until softened.

Sprinkle flour into the pan and cook until no longer raw. Gradually add milk, stirring until thickened. Season with salt and pepper.