1. Heat a wok over high heat for 30 seconds. Add the peanut oil and onions, and cook for 7 minutes, stirring and turning the onions often to prevent burning and to ensure even browning. Reduce the heat to medium and cook, stirring often, for 15 minutes more, or until the onions turn light brown. Turn off the heat. Strain the oil through a fine-mesh strainer into a heatproof bowl, pressing the onions with a ladle as they drain. Allow the oil to cool to room temperature. Set the fried onions aside to cool. Pour the cooled oil into a sterilized glass jar and close tightly. The oil will keep at room temperature for 1 week or refrigerated for up to 3 months. Transfer the fried onions to a plastic container, cover, and refrigerate. They will keep for up to 3 months.