Trim the ends off the cucumbers and discard. Slice the cucumbers thinly, about the thickness of a coin. I slice mine by hand but you can use a food processor or mandoline.
Mix the cucumber and onion in a non-reactive* bowl.
Mix the salt with the boiling water. Some of the salt will dissolve, but not all of it.Pour the salt and water over the cucumber mixture, mix to distribute and leave for 3 hours, turning the mixture occasionally.
Tip the cucumber and onion into a colander and press the mixture down with the back of a large spoon to remove as much liquid as possible.
For the pickling liquid, mix all the ingredients in a non-reactive medium-sized saucepan. Bring the mixture to a simmer over a medium heat, stirring to dissolve the sugar.
Tip the cucumber and onion into the pickling liquid and simmer 2 minutes. Stir several times.
Remove from the heat and leave the mixture to cool in the saucepan.
Spoon the mixture into sterilised jars*, ensuring the mixture is covered with pickling liquid. Do not overfill the jars as the liquid should not touch the lids.Once a jar is opened, store it in the refrigerator.
*See the notes regarding a non-reactive bowl and saucepan in the main notes above.*I have also used young zucchini to make this pickle.*The onion weight is roughly 200gm.*The tablespoon is 20ml size.*To produce the best-flavoured pickle it is important to use good quality vinegar*To sterilise jars, heat the oven to 130C/ 270F, place the jars and metal lids on the racks and leave them for 20 minutes.