Remove the stems from the shiitake mushrooms and slice the caps in half. If the mushrooms are very big, slice them in quarters.
Heat one tablespoon of oil in a wok over high heat. Once it is lightly smoking, add the shiitake mushrooms. Cook for about 3 minutes until they turn golden and shrink by about 20% in size. Make sure you are constantly stirring to allow steam to escape.
Reduce the heat to medium and push the mushrooms to one side of the wok. Add one tablespoon of oil into the empty space. Add the minced garlic and cook it in the oil for 30 seconds. Then, mix the garlic and mushrooms together.
Add the soy sauce, oyster sauce, and a teaspoon of water and continue cooking for 1-2 minutes. Serve immediately over rice.