Ingredients

1 tablespoon olive oil

500g onions sliced

2kg ripe tomatoes chopped

1 teaspoon sea salt

1 cup red wine vinegar

375gm brown sugar

2 tablespoons whole grain mustard

Makes about 4 cups

Method

Heat olive oil in a large pot over medium heat and add the onions and cook until soft. Add the tomatoes and bring to the boil.

Add the rest of the ingredients, lower the heat and simmer uncovered for one hour or until reduced to a thick, jammy consistency.

Spoon into sterilised jars and seal.