2 kilograms ripe tomatoes, chopped
2 large onions, chopped
1 tablespoon salt
1 tablespoon curry powder
1 tablespoon dry mustard powder
1 teaspoon chilli flakes (optional)
1 cup white wine vinegar
1 cup sugar
2 tablespoons cornflour
1-2 tablespoons cold water
Place tomatoes and onions in a bowl and sprinkle with salt. Leave to stand for at least 4 hours and up to 12 hours. Strain off and discard the liquid produced.
Place drained tomatoes and onions in a large preserving pan with curry powder, mustard powder, chilli powder (if using) and vinegar. Bring to the boil and boil about 15 minutes. Stir in sugar until dissolved, then continue to boil gently for another 1 hour 15 minutes.
Mix cornflour to a paste with the cold water. Stir into the boiling sauce until slightly thickened. Cook through for about 2 minutes. Remove from heat, pour into hot sterilised jars* and seal with lids. When the lids suck down it means the jars are sealed. These jars can last for a year. Those jars that don’t seal properly can be stored in the fridge and used first.
*Sterilised means putting clean jars into an oven at 100°C for 15 minutes. I put the lids in a pot of boiling water and boil for 5 minutes.