Combine all the in a large, microwavable bowl.
Pour in the water and cover loosely with a microwave-safe plate or lid.
Microwave at full power (800W) for 10–15 minutes, stirring every 5 minutes, until the apples and onions have completely softened.
Carefully use a hand-held immersion blender to purée the mixture until it reaches a smooth consistency.
Place the lid back on loosely and microwave again for a further 5–10 minutes. The chutney is ready when it's thick and a spoonful placed on a cold plate doesn't run.
Taste the chutney and add more salt for savouriness or sugar for sweetness as needed to achieve your desired balance.
Allow the chutney to cool completely before transferring it to a sterilised 1kg (2.2 lb) jar. This will keep for up to a month in the fridge.