Heat a wok until just smoking. Add the oil and, when hot, stir-fry the ginger and garlic until fragrant. Add the sausage and stir-fry for another minute, then add the shrimp, mushrooms and peanuts and toss together. Add the rice and oyster and soy sauces, and work the mixture together thoroughly with a spoon, then transfer to a clay pot.
Add the stock to the rice and st