Cambodian beef lok lak: stir fried soy sauce beef served with lettuce and tomatoes!
Combine the soy sauce, the oyster sauce, the fish sauce, the mashed garlic, the sugar and the tomato ketchup in a shallow (baking) dish or deep plate. Season with some pepper and stir.
Slice the steak into bite-size bits and add it to the marinade. Stir well until the steak has been fully coated. Then cover the plate or dish with some cling film and place it in the fridge for at least an hour to marinate.
Pour the vegetable oil in a medium non-stick pan and place it over medium heat. Once the oil is hot, add the marinated beef.