In a large bowl combine the chopped cucumbers, cauliflower, red peppers and peeled onions.

In another bowl mix together the salt and water and pour over veggies, tossing the veggies to make sure they are all coated in the brine.  I cover them with a tea towel, and then put a dinner plate on top.  Let stand overnight at room temperature.

Sterilize five 1 quart jars with lids and rings in a water bath (save the warm water bath for later,  you will need it)

Transfer the vegetables and brine to a large pot and set over medium heat. Bring just to a simmer, but remove from the heat before they come to a boil. Pour into a colander and drain thoroughly.

Dry out the large pot and stir together the flour, mustard powder, sugar and turmeric. Stir in just enough apple cider vinegar to make a smooth paste, then stir in the remaining vinegar. Bring to a boil, stirring frequently, and boil until thick and creamy, 10 to 15 minutes. Add the vegetables and stir the mixture together.  Avoid overcooking the veggies as you don’t want them to turn to mush.

Pack into hot 1 quart jars, filling to 1/2 inch of the rim and wiping off the rims with a clean, damp cloth. Seal with lids and rings. Process in a hot water bath of simmering water for 10 minutes,  remove from water and cool to room temperature. Refrigerate any jars that do not seal properly and consume within two weeks.