Wearing rubber gloves for protection, remove stalks and seeds from the chillies. Place in a food processor and chop finely. Peel and finely chop the onions.
Peel, core and chop apples. Place in a pan with chillies, onions, and remaining ingredients. Stir over low heat until mixture starts to boil. Simmer for about 40 minutes until all ingredients are soft and sauce has thickened. Using a small funnel or jug, fill sauce into hot sterilised bottles and seal.