Dice the mushrooms into 1 cm (½ inch) cubes. Heat 30 ml (1 fl oz) garlic oil in a frying pan over medium heat. Add the mushrooms, season with salt and pepper and cook until softened. Drain and place on a baking tray lined with baking paper. Dry in a dehydrator at 60°C (140°F) for 1 hour. Alternatively, place in the oven on the lowest temperature and leave until completely dry. When ready to serve, heat the remaining garlic oil in a small frying pan over low heat and warm the dehydrated mushrooms.