Stir together the salt and water in a non-reactive bowl until the salt has dissolved. Add onions, cover and let stand at room temperature for 24 hours.
In a saucepan combine the brown sugar and 2 1/2 cups of the malt vinegar and heat.
In a small bowl, mix together the rest of the dry ingredients, add the remaining 1/4 cup of malt vinegar and mix to a smooth paste. Stir the paste into the hot vinegar and cook stirring until mixture thickens about 2 minutes. Once thick, set aside and allow to cool.
Drain the onions, and pack into two sterilized 1 litre jars. Pour the warm sauce over the onions to cover. Seal with lids and rings. Leave in a cool, dark place 4 to 6 weeks to allow the flavors to develop.
I gave this recipe a go and while the wait was long it was worth it! The batch was eaten in about 3 months and remained absolutely fantastic however I wondered how I could use the remaining pickling sauce .....well I marinated BBQ lamb chops for a day and all the flavours were there including the long gone onions and the lamb was not over-powered in the slightest. Still have enough sauce left to try it on beef or chicken,.. maybe pork? So give this a try...waste not want not and really worth it! - 25 Feb 2015