Method:
Spread the cauliflower out on a large tray and sprinkle with salt. Cover with cling film and leave in a cool place overnight
Next day, rinse the cauliflower under cold running water and drain well.
Put both the vinegars into a wide pan, bring to the boil and boil steadily for about 10 minutes until reduced by a quarter to 1275ml.
Mix the sugar, turmeric and mustard together, then add to the vinegar and stir until the sugar has dissolved. Simmer for a few minutes.
Stir in the cornflour mixture and cook, stirring, for another 4-5 minutes, to cook out the cornflour. Add Salt to taste
Add the cauliflower and onions and stir well. Simmer for 5 minutes, then take off the heat and add the cornichons, stirring the mixture well.
Cool and Tub up.