In a heavybased pan heat the oil and cook the mushrooms and garlic for about 5 minutes until softened. Stir in the rice and cook for a minute.
Place the stock cube in a jug and make up to 600ml /1 pint. Pour over the mushrooms and rice, add the soy sauce, stir together and bring to the boil. Once boiling put on the lid, turn down the heat to its lowest setting and cook for 20 minutes, then remove from the heat and leave to steam for another 10 minutes before lifting the lid.
Fluff the cooked rice and season to taste if it needs it.