How to make it
Mix heavy cream and Otafuku Katsu Sauce. Stir well.
Add 1 tbsp oil to a pan, then cook onion and mushrooms on medium-high heat for 5 minutes, or until cooked well.
Remove onions and mushrooms from heat and then add to katsu mixture. Stir and put aside.
Season ground beef with salt and pepper to taste, and then form into a patty.
Add 1 tbsp oil to the pan and make a small indent in the center of the patty. Cook for about 5 minutes on each side, or until browned.
Cook egg in remaining grease, removing from heat before yolk is cooked all the way through.
Add beef patty to cooked rice on a plate and top with egg. Pour sauce over beef patty and garnish with green onion as desired. Serve immediately.