In a large bowl mix together all of the ingredients to make the hamburgers and knead together until they are combined well.

Divide the hamburger mixture into 8 equal pieces and form those pieces into small round patties at least 2cm thick.

Fry the patties in a hot, oiled saute pan until they begin to form a brown crust on one side, about 2-3 minutes, then flip and cook on the other side for another 2 minutes then set aside on a plate while you make the gravy.

To the saute pan add a small amount more vegetable oil then put in the mushrooms and onions and saute until they caramelize, at least 10-15 minutes.

Add the stock, soy sauce, Worcestershire sauce, and potato starch to deglaze the saute pan and cook gravy mixture just until thickened then turn off the heat.

Place the hamburgers back in the gravy and coat them in the gravy before serving.

Plate the Loco Moco by placing a mound of rice on the plate then topping with a hamburger and coating with as much gravy as desire and topping with a fried egg.