Place onions into Thermomix bowl and chop 3 sec/sp 5.
Add tomatoes amd mix with spatual. Chop 3 sec/sp 5. Repeat for 1 to 2 more seconds if necessary.
Place into a large container and sprinkle with the salt.
Refrigerate overnight.
Next day, drain well and place into a large pan with the sugar. Pour over enough vinegar to cover and bring to the boil. Boil together for 5 minutes, stirring regularly.
Mix the curry powder and mustard to a paste with a little extra vinegar and add.
Simmer gently for around 2 hours, stirring regularly to ensure it doesn't catch on the bottom of the pan.
Thicken with cornflour paste - around 2 -3 Tbsp of cornflour. Place into sterlised jars and seal tightly. Turn jars upside down for 30 minutes. When turned upright, lids should pop down.
Notes
Use in sandwiches and as a condiment for cold meats. Add to gravy when serving rissoles or meat loaf.
Recipe by ThermoGourmand at https://thermogourmand.com.au/index.php/2023/03/09/cwa-tomato-relish/