Add diced onions and apples along with sultanas, grated ginger, spices and sea salt to a preserving pan.
Pour in cider vinegar, stir well and slowly bring to the boil. Adjust heat to give a simmer.
Cover with a lid and simmer for 30 minutes.
Remove pan from the heat and stir in the sugar.
Return the pan, without lid, to a low heat. Let the chutney mixture simmer for at least 1 1/2 to 2 hours. Stir every now and then to prevent sticking to the bottom of the pan.
The chutney is ready when the liquid has reduced and is thick and glossy. Check for thickness by drawing a silicone spatula or wooden spoon through the chutney mixture. Your chutney is ready when it parts to reveal the base of the preserving pan for a few seconds.
Ladle into sterilised jars and label when cold.